feat(班级PK): 班级 PK 页重做：两个班看比分和每道题谁赢，三个班以上看题目对照格，学生也能比

- 两个班：大比分 + 一次就对副比分，每道题左右两根条、差得最多的在上，下面每周人均和全班分布
- 三个班以上：一行一道题、一格一个班，越深做对的人越多，皇冠是这道做得最好的班；右边谁领先的题多和赛跑
- 学生自己的班标「你们班」，输掉的题写「再 N 人做对就打平」；AI 分析只给老师，直接在页面里出
- 去掉综合分、雷达图、十张柱状图；手机版按稿改成上下排和页签
- 排名页、班级对抗、班级详情的入口对登录的人都开放，带上当前的班

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/src/routes/ai.ts

@@ -23,7 +23,7 @@ import { generateFilteredHint } from "../services/hint-filter"
 import { buildDetail, buildDuration, listSolved } from "../services/learning-stats"
 import { decideHintLevel } from "../services/hint-level"
 import { hintDiagnosis, hintPrompt, referenceAnswer } from "../services/hint-diagnosis"
-import { classDetail } from "../services/ranking"
+import { classDetail, classPk } from "../services/ranking"
 import { consumeToken } from "../services/throttling"
 import { calendarDay, dayNumber, dayText, localTime, localWeekday } from "../time"
 import { countFailedSubmissions, isTeacherOrAbove, asRecord, queryInteger } from "./helpers"
@@ -385,8 +385,46 @@ aiRoutes.post("/ai/class-pk-analysis", requireAuth, async (c) => {
   if (!parsed.success) return parsed.response
   const limited = await throttleAi(c)
   if (limited) return limited
+  // 数字和页面上的是同一份（services/ranking.ts 的 classPk），不再由前端整包传上来
+  const pk = await classPk([...new Set(parsed.data.classNames)], parsed.data.period, null)
+  const label = (name: string) => `${name.slice(0, 2)}计算机${name.slice(2)}班`
+  const facts = {
+    时间段: parsed.data.period === "week" ? "这周" : "这学期",
+    各班: pk.classes.map((item) => ({
+      班级: label(item.className),
+      人数: item.members,
+      人均做对: item.perCapita,
+      中间那位做对: item.median,
+      做对过题的人: item.solvedMembers,
+      一次就对百分比: item.firstPercent,
+      同一批题里领先几道: item.lead,
+      这学期每周人均新做对: item.weekly,
+    })),
+    同一批题: pk.problems.map((problem) => ({
+      题目: problem.title,
+      各班: problem.cells.map((cell, index) =>
+        cell
+          ? {
+              班级: label(pk.classes[index]!.className),
+              做对的人占全班百分比: cell.percent,
+              一次就对百分比: cell.firstPercent,
+              交过的人: cell.tried,
+              最好: cell.best,
+            }
+          : { 班级: label(pk.classes[index]!.className), 没布置: true },
+      ),
+    })),
+    只有一个班布置过的题数: pk.solo.length,
+  }
   return streamChat(
-    "你是编程教育数据分析专家。根据多个班级 OJ 对比数据，从排名、参与度、典型学生水平、均衡性、梯队、提交质量和教学建议七方面输出中文 Markdown 报告。",
-    `${parsed.data.timeRangeLabel}\n${JSON.stringify(parsed.data.comparisons)}`,
+    [
+      "你是编程课老师的助教。下面是几个班在 OJ 上的对比数据（JSON）。各班进度不同、布置的题不一样，",
+      "所以比较以「同一批题」（至少两个班都布置过的题）为主，人均做对只作参考。",
+      "用中文 Markdown 写一份给老师看的简短分析，分三到四段，每段一两句，段首加粗：",
+      "**整体**（人均和同一批题里各班领先几道，人均差距有多少是进度造成的）、",
+      "**差得最多的题**（点题目名，哪个班明显低）、**一次就对**（哪个班更稳、哪个班靠多交几次）、",
+      "**建议**（下节课能直接做的事）。用大白话，不要出现四分位数、标准差这类统计词，不要编数据里没有的数字。",
+    ].join(""),
+    JSON.stringify(facts),
   )
 })

apps/api/src/routes/classroom.ts

@@ -1,6 +1,5 @@
 import {
   isSqlProblem,
-  classComparisonRequestSchema,
   STUDENT_ROLES,
   classLessonRequestSchema,
   type ClassActivity,
@@ -8,26 +7,11 @@ import {
   type ClassBoardStudent,
   type ClassLesson,
   type ClassActivityProblem,
-  type ClassComparison,
-  type ClassComparisonResponse,
   type LastVisit,
   type LessonLanguage,
   FLOWCHART_PASS_GRADES,
 } from "@oj2/contract"
-import {
-  and,
-  asc,
-  desc,
-  eq,
-  gte,
-  inArray,
-  isNotNull,
-  isNull,
-  like,
-  lt,
-  lte,
-  sql,
-} from "drizzle-orm"
+import { and, asc, desc, eq, gte, inArray, isNotNull, isNull, lt, sql } from "drizzle-orm"
 import { Hono } from "hono"
 
 import { requireAuth, requireTeacher, type AppEnv } from "../auth/middleware"
@@ -37,75 +21,9 @@ import { failure, parseBody, success } from "../http"
 import { JudgeStatus } from "../judge/status"
 import { accepted } from "../services/learning-stats"
 import { calendarDay, dayStart, localTime } from "../time"
-import { rounded } from "./helpers"
 
 export const classroomRoutes = new Hono<AppEnv>()
 
-interface ClassUser {
-  userId: number
-  username: string
-  className: string
-  acceptedNumber: number
-  submissionNumber: number
-}
-
-/**
- * 入班学生的 AC/提交数。`gradePrefix` 是年级（班号形如 `241` = 24 级 1 班），
- * 走 SQL 的 like 而不是拉全表再在内存里 startsWith —— 班级榜每换一次年级就要跑一遍，
- * 没必要每次都把全校一千多号人搬进进程。年级在调用处已校验为纯数字，不含 like 通配符。
- */
-async function loadClassUsers(classNames?: string[], gradePrefix?: string) {
-  const filters = [
-    eq(schema.user.isDisabled, false),
-    inArray(schema.user.adminType, [...STUDENT_ROLES]),
-    sql`${schema.user.className} is not null`,
-  ]
-  if (classNames) filters.push(inArray(schema.user.className, classNames))
-  if (gradePrefix) filters.push(like(schema.user.className, `${gradePrefix}%`))
-  const rows = await db
-    .select({
-      userId: schema.user.id,
-      username: schema.user.username,
-      className: schema.user.className,
-      acceptedNumber: schema.userProfile.acceptedNumber,
-      submissionNumber: schema.userProfile.submissionNumber,
-    })
-    .from(schema.user)
-    .innerJoin(schema.userProfile, eq(schema.userProfile.userId, schema.user.id))
-    .where(and(...filters))
-  return rows.filter((row): row is ClassUser => row.className !== null)
-}
-
-function mean(values: number[]) {
-  return values.length ? values.reduce((sum, value) => sum + value, 0) / values.length : 0
-}
-
-function median(values: number[]) {
-  if (!values.length) return 0
-  const sorted = [...values].sort((a, b) => a - b)
-  const middle = Math.floor(sorted.length / 2)
-  return sorted.length % 2 ? sorted[middle]! : (sorted[middle - 1]! + sorted[middle]!) / 2
-}
-
-function quantile(values: number[], p: number) {
-  if (values.length <= 1) return values[0] ?? 0
-  const sorted = [...values].sort((a, b) => a - b)
-  const position = (sorted.length + 1) * p - 1
-  if (position <= 0) return sorted[0]!
-  if (position >= sorted.length - 1) return sorted.at(-1)!
-  const lower = Math.floor(position)
-  const fraction = position - lower
-  return sorted[lower]! + (sorted[lower + 1]! - sorted[lower]!) * fraction
-}
-
-function sampleStdDev(values: number[]) {
-  if (values.length <= 1) return 0
-  const average = mean(values)
-  return Math.sqrt(
-    values.reduce((sum, value) => sum + (value - average) ** 2, 0) / (values.length - 1),
-  )
-}
-
 /**
  * 同班同一天有这么多人做过，就算「班里在做」。2025 秋的实测分布是两极的：
  * (班级, 日, 题) 要么只有 1 个人（自己在刷），要么 13 人以上（老师点的题），
@@ -892,111 +810,3 @@ classroomRoutes.put("/classroom/lesson", requireTeacher, async (c) => {
     })
   return success(c, null)
 })
-
-classroomRoutes.post("/classes/comparison", async (c) => {
-  const parsed = await parseBody(c, classComparisonRequestSchema, "At least one class is required")
-  if (!parsed.success) return parsed.response
-  const users = await loadClassUsers(parsed.data.classNames)
-  const allAc = users.map((user) => user.acceptedNumber)
-  const globalQ1 = quantile(allAc, 0.25)
-  const globalQ3 = quantile(allAc, 0.75)
-  const byClass = new Map<string, ClassUser[]>()
-  for (const user of users)
-    byClass.set(user.className, [...(byClass.get(user.className) ?? []), user])
-
-  let recentByUser = new Map<number, Set<number>>()
-  let recentSubmissionCount = new Map<string, number>()
-  const hasTimeRange = Boolean(parsed.data.startTime && parsed.data.endTime)
-  if (hasTimeRange) {
-    const rows = await db
-      .select({
-        userId: schema.submission.userId,
-        problemId: schema.submission.problemId,
-        result: schema.submission.result,
-      })
-      .from(schema.submission)
-      .where(
-        and(
-          inArray(
-            schema.submission.userId,
-            users.map((user) => user.userId),
-          ),
-          gte(schema.submission.createTime, parsed.data.startTime!),
-          lte(schema.submission.createTime, parsed.data.endTime!),
-        ),
-      )
-    const userClass = new Map(users.map((user) => [user.userId, user.className]))
-    for (const row of rows) {
-      const className = userClass.get(row.userId)
-      if (!className) continue
-      recentSubmissionCount.set(className, (recentSubmissionCount.get(className) ?? 0) + 1)
-      if ([JudgeStatus.ACCEPTED, JudgeStatus.AST_CHECK_FAILED].includes(row.result as 0 | 10)) {
-        const set = recentByUser.get(row.userId) ?? new Set<number>()
-        set.add(row.problemId)
-        recentByUser.set(row.userId, set)
-      }
-    }
-  }
-
-  const comparisons = [...byClass].map(([className, members]) => {
-    const ac = members.map((member) => member.acceptedNumber).sort((a, b) => b - a)
-    const submissions = members.map((member) => member.submissionNumber).sort((a, b) => b - a)
-    const userCount = members.length
-    const topCount = Math.max(1, Math.ceil(userCount * 0.1))
-    const bottomCount = topCount
-    const middle = topCount + bottomCount < userCount ? ac.slice(topCount, -bottomCount) : ac
-    const totalAc = ac.reduce((sum, value) => sum + value, 0)
-    const totalSubmission = submissions.reduce((sum, value) => sum + value, 0)
-    const base: ClassComparison = {
-      className,
-      userCount,
-      totalAc,
-      totalSubmission,
-      avgAc: rounded(mean(ac)),
-      medianAc: rounded(median(ac)),
-      q1Ac: rounded(quantile(ac, 0.25)),
-      q3Ac: rounded(quantile(ac, 0.75)),
-      iqr: rounded(quantile(ac, 0.75) - quantile(ac, 0.25)),
-      stdDev: rounded(sampleStdDev(ac)),
-      top10Avg: rounded(mean(ac.slice(0, topCount))),
-      middle80Avg: rounded(mean(middle)),
-      bottom10Avg: rounded(mean(ac.slice(-bottomCount))),
-      excellentRate: rounded((ac.filter((value) => value >= globalQ3).length / userCount) * 100),
-      passRate: rounded((ac.filter((value) => value >= globalQ1).length / userCount) * 100),
-      activeRate: rounded((submissions.filter((value) => value > 0).length / userCount) * 100),
-      acRate: totalSubmission > 0 ? rounded((totalAc / totalSubmission) * 100) : 0,
-      compositeScore: 0,
-    }
-    if (hasTimeRange) {
-      const recent = members
-        .map((member) => recentByUser.get(member.userId)?.size ?? 0)
-        .sort((a, b) => b - a)
-      base.recentTotalAc = recent.reduce((sum, value) => sum + value, 0)
-      base.recentTotalSubmission = recentSubmissionCount.get(className) ?? 0
-      base.recentAvgAc = rounded(mean(recent))
-      base.recentMedianAc = rounded(median(recent))
-      base.recentTop10Avg = rounded(
-        mean(recent.slice(0, Math.max(1, Math.ceil(recent.length * 0.1)))),
-      )
-      base.recentActiveCount = recent.filter((value) => value > 0).length
-    }
-    return base
-  })
-  const maxMedian = Math.max(1, ...comparisons.map((item) => item.medianAc))
-  const maxMiddle = Math.max(1, ...comparisons.map((item) => item.middle80Avg))
-  for (const item of comparisons) {
-    item.compositeScore = rounded(
-      0.4 * ((item.medianAc / maxMedian) * 100) +
-        0.15 * ((item.middle80Avg / maxMiddle) * 100) +
-        0.2 * item.activeRate +
-        0.15 * item.passRate +
-        0.1 * item.excellentRate,
-      1,
-    )
-  }
-  comparisons.sort((a, b) => b.compositeScore - a.compositeScore || b.medianAc - a.medianAc)
-  return success(c, {
-    comparisons,
-    hasTimeRange,
-  } satisfies ClassComparisonResponse)
-})

apps/api/src/routes/ranking.ts

@@ -1,4 +1,5 @@
 import {
+  classPkPeriodSchema,
   rankHiddenRequestSchema,
   rankPeriodSchema,
   rankScopeSchema,
@@ -13,7 +14,7 @@ import {
 import { and, countDistinct, desc, eq, gte, inArray, isNotNull, ne } from "drizzle-orm"
 import { Hono } from "hono"
 
-import { optionalAuth, requireTeacher, type AppEnv } from "../auth/middleware"
+import { optionalAuth, requireAuth, requireTeacher, type AppEnv } from "../auth/middleware"
 import { db, schema } from "../db"
 import { failure, parseBody, success } from "../http"
 import { dayStart, termStart, weekStart } from "../time"
@@ -21,7 +22,10 @@ import {
   audienceWhere,
   classBattle,
   classDetail,
+  classPk,
   loadEntrants,
+  PK_MAX_CLASSES,
+  pkPartner,
   rankedStudents,
   standings,
   WEEK_MS,
@@ -252,6 +256,38 @@ rankingRoutes.get("/rankings/class-detail", optionalAuth, async (c) => {
   return success(c, await classDetail(className, isTeacherOrAbove(c.get("user"))))
 })
 
+/**
+ * 班级 PK（设计稿「班级 PK 重设计」定稿）：`classes` 逗号分隔。谁登录了都能看 —— 只有班级
+ * 层面的数，没有点名到人。只给一个班（或者不给，用自己的班 / 老师默认的班）就配一个对手，
+ * 见 `pkPartner`。
+ */
+rankingRoutes.get("/rankings/pk", requireAuth, async (c) => {
+  const user = c.get("user")!
+  const period = classPkPeriodSchema.safeParse(c.req.query("period") ?? "term")
+  if (!period.success) return failure(c, 400, "invalid-query", "时间段不对")
+  const requested = [
+    ...new Set(
+      (c.req.query("classes") ?? "")
+        .split(",")
+        .map((name) => name.trim())
+        .filter((name) => name && name.length <= 32),
+    ),
+  ]
+  if (requested.length > PK_MAX_CLASSES)
+    return failure(c, 400, "too-many-classes", `一次最多比 ${PK_MAX_CLASSES} 个班`)
+
+  const isTeacher = isTeacherOrAbove(user)
+  const mine = isTeacher ? null : user.className || null
+  const classNames = requested.length
+    ? requested
+    : [isTeacher ? await defaultClassFor(user.id) : mine].filter((name): name is string => !!name)
+  if (classNames.length === 1) {
+    const partner = await pkPartner(classNames[0]!)
+    if (partner) classNames.push(partner)
+  }
+  return success(c, await classPk(classNames, period.data, mine))
+})
+
 /** 本班每周冠军：最近几个已经结束的周，每周新做对最多的那个人（一样多先做到的） */
 rankingRoutes.get("/rankings/champions", optionalAuth, async (c) => {
   const className = await resolveGroup(c.get("user"), "class", c.req.query("className")?.trim())

apps/api/src/services/ranking.ts

@@ -2,6 +2,10 @@ import {
   STUDENT_ROLES,
   type ClassBattleItem,
   type ClassDetail,
+  type ClassPk,
+  type ClassPkCell,
+  type ClassPkClass,
+  type ClassPkPeriod,
   type RankScope,
 } from "@oj2/contract"
 import {
@@ -15,6 +19,7 @@ import {
   like,
   min,
   ne,
+  sql,
   type SQL,
 } from "drizzle-orm"
 
@@ -308,3 +313,221 @@ export async function classDetail(className: string, withCare: boolean): Promise
     care,
   } satisfies ClassDetail
 }
+
+/** 一次最多比几个班（对照格再宽就放不下了） */
+export const PK_MAX_CLASSES = 8
+
+interface PkPair {
+  className: string
+  problemId: number
+  solved: boolean
+  firstSolved: boolean
+  submissions: number
+}
+
+/**
+ * 这几个班从 `since` 起每个人每道题：交了几次、做对没有、第一次交就对没有。比赛里的提交不算，
+ * 入榜人群和排名页一样（不计入排名的人不算）。「第一次」是这段时间里的第一次。
+ */
+async function pkPairs(classNames: string[], since: string): Promise<PkPair[]> {
+  const rows = await db
+    .select({
+      className: schema.user.className,
+      problemId: schema.submission.problemId,
+      submissions: count(),
+      solved: sql<boolean>`bool_or(${inArray(schema.submission.result, SOLVED_RESULTS)})`,
+      first: sql<number>`(array_agg(${schema.submission.result} order by ${schema.submission.createTime}, ${schema.submission.id}))[1]`,
+    })
+    .from(schema.submission)
+    .innerJoin(schema.user, eq(schema.user.id, schema.submission.userId))
+    .where(
+      and(
+        rankedStudents,
+        inArray(schema.user.className, classNames),
+        isNull(schema.submission.contestId),
+        gte(schema.submission.createTime, since),
+      ),
+    )
+    .groupBy(schema.user.className, schema.submission.userId, schema.submission.problemId)
+  return rows.map((row) => ({
+    className: row.className!,
+    problemId: row.problemId,
+    solved: row.solved,
+    firstSolved: (SOLVED_RESULTS as number[]).includes(row.first),
+    submissions: row.submissions,
+  }))
+}
+
+/** 每个班布置过哪些题：过半的人交过就算 */
+function assignedSets(pairs: PkPair[], members: Map<string, number>) {
+  const tried = new Map<string, Map<number, number>>()
+  for (const pair of pairs) {
+    const byProblem = tried.get(pair.className) ?? new Map<number, number>()
+    byProblem.set(pair.problemId, (byProblem.get(pair.problemId) ?? 0) + 1)
+    tried.set(pair.className, byProblem)
+  }
+  const sets = new Map<string, Set<number>>()
+  for (const [className, byProblem] of tried) {
+    const n = members.get(className) ?? 0
+    sets.set(
+      className,
+      new Set([...byProblem].filter(([, people]) => n > 0 && people * 2 >= n).map(([id]) => id)),
+    )
+  }
+  return sets
+}
+
+function memberCounts(entrants: Entrant[]) {
+  const members = new Map<string, number>()
+  for (const entrant of entrants)
+    members.set(entrant.className!, (members.get(entrant.className!) ?? 0) + 1)
+  return members
+}
+
+/**
+ * 只给了一个班（或者没给、用看的人自己的班）时，配一个对手：同年级在用的班里，和它一起
+ * 布置过的题最多的那个；一样多挑班级对抗里排得更前的（用户 2026-10-10 定的）。
+ * 同年级没有别的在用的班就不配。
+ */
+export async function pkPartner(className: string) {
+  const { term, entrants } = await classedEntrants()
+  const battle = battleFrom(entrants)
+  const grade = className.slice(0, 2)
+  const candidates = battle.filter(
+    (item) => item.className !== className && item.className.slice(0, 2) === grade,
+  )
+  if (!candidates.length) return null
+  const names = [className, ...candidates.map((item) => item.className)]
+  const sets = assignedSets(
+    await pkPairs(names, term),
+    memberCounts(entrants.filter((entrant) => names.includes(entrant.className!))),
+  )
+  const mine = sets.get(className) ?? new Set<number>()
+  const common = (name: string) => [...(sets.get(name) ?? [])].filter((id) => mine.has(id)).length
+  return candidates.sort((a, b) => common(b.className) - common(a.className) || a.rank - b.rank)[0]!
+    .className
+}
+
+/**
+ * 班级 PK 的全部数字（页面和 AI 分析共用）。人均、分布按 `period` 算；每周人均（赛跑）
+ * 一直按这学期，横轴才有东西。
+ */
+export async function classPk(
+  classNames: string[],
+  period: ClassPkPeriod,
+  mine: string | null,
+): Promise<ClassPk> {
+  const { term, entrants: all } = await classedEntrants()
+  const since = period === "week" ? weekStart() : term
+  const sinceMs = Date.parse(since)
+  const battle = battleFrom(all)
+  const entrants = all.filter((entrant) => classNames.includes(entrant.className!))
+  const members = memberCounts(entrants)
+  const pairs = await pkPairs(classNames, since)
+  const assigned = assignedSets(pairs, members)
+
+  const firstWeek = Date.parse(weekStart(term))
+  const thisWeek = Date.parse(weekStart())
+  const weeks: number[] = []
+  for (let from = firstWeek; from <= thisWeek; from += WEEK_MS) weeks.push(from)
+
+  // 每道题、每个班：交过 / 做对 / 一次就对 / 提交次数
+  const cells = new Map<
+    number,
+    Map<string, Omit<ClassPkCell, "percent" | "firstPercent" | "best">>
+  >()
+  for (const pair of pairs) {
+    if (!assigned.get(pair.className)?.has(pair.problemId)) continue
+    const byClass = cells.get(pair.problemId) ?? new Map()
+    const cell = byClass.get(pair.className) ?? { tried: 0, solved: 0, firstTry: 0, submissions: 0 }
+    cell.tried++
+    if (pair.solved) cell.solved++
+    if (pair.firstSolved) cell.firstTry++
+    cell.submissions += pair.submissions
+    byClass.set(pair.className, cell)
+    cells.set(pair.problemId, byClass)
+  }
+  const titles = cells.size
+    ? await db
+        .select({
+          id: schema.problem.id,
+          displayId: schema.problem.displayId,
+          title: schema.problem.title,
+        })
+        .from(schema.problem)
+        .where(inArray(schema.problem.id, [...cells.keys()]))
+    : []
+  const titleOf = new Map(titles.map((row) => [row.id, row]))
+
+  const lead = new Map<string, number>()
+  const problems: ClassPk["problems"] = []
+  const solo: ClassPk["solo"] = []
+  for (const [problemId, byClass] of [...cells].sort((a, b) => a[0] - b[0])) {
+    const meta = titleOf.get(problemId)
+    if (!meta) continue
+    if (byClass.size === 1) {
+      const [className] = byClass.keys()
+      solo.push({ problemId, displayId: meta.displayId, title: meta.title, className: className! })
+      continue
+    }
+    const row = classNames.map((className) => {
+      const cell = byClass.get(className)
+      if (!cell) return null
+      return {
+        ...cell,
+        percent: Math.round((cell.solved / members.get(className)!) * 100),
+        firstPercent: Math.round((cell.firstTry / cell.tried) * 100),
+        best: false,
+      }
+    })
+    const top = Math.max(...row.map((cell) => cell?.percent ?? -1))
+    row.forEach((cell, index) => {
+      if (!cell || cell.percent !== top) return
+      cell.best = true
+      lead.set(classNames[index]!, (lead.get(classNames[index]!) ?? 0) + 1)
+    })
+    problems.push({ problemId, displayId: meta.displayId, title: meta.title, cells: row })
+  }
+
+  const classes = classNames.map((className) => {
+    const people = entrants.filter((entrant) => entrant.className === className)
+    const solved = people.map((entrant) => entrant.times.filter((time) => time >= sinceMs).length)
+    const own = pairs.filter((pair) => pair.className === className)
+    return {
+      className,
+      members: people.length,
+      perCapita: people.length ? rounded(average(solved), 1) : 0,
+      median: median(solved),
+      solvedMembers: solved.filter((value) => value > 0).length,
+      firstPercent: own.length
+        ? Math.round((own.filter((pair) => pair.firstSolved).length / own.length) * 100)
+        : null,
+      lead: lead.get(className) ?? 0,
+      battleRank: battle.find((item) => item.className === className)?.rank ?? null,
+      distribution: solved,
+      weekly: weeks.map((from) =>
+        people.length
+          ? rounded(
+              average(
+                people.map(
+                  (entrant) =>
+                    entrant.times.filter((time) => time >= from && time < from + WEEK_MS).length,
+                ),
+              ),
+              1,
+            )
+          : 0,
+      ),
+    } satisfies ClassPkClass
+  })
+
+  return {
+    period,
+    start: since,
+    weeks: weeks.map((from) => new Date(from).toISOString()),
+    classes,
+    mine,
+    problems,
+    solo,
+  } satisfies ClassPk
+}

apps/web/src/oj/api.ts

@@ -14,9 +14,10 @@ import {
   type ClassBoard,
   type ClassLesson,
   type KnowledgeMap,
-  type ClassComparisonResponse,
   type ClassBattleItem,
   type ClassDetail,
+  type ClassPk,
+  type ClassPkPeriod,
   type RankBoard,
   type RankPeriod,
   type RankScope,
@@ -304,11 +305,10 @@ export function getLastVisit() {
   return api.get<LastVisit>("me/last-visit")
 }
 
-export function getClassPK(classNames: string[], startTime?: string, endTime?: string) {
-  return api.post<ClassComparisonResponse>("classes/comparison", {
-    classNames,
-    ...(startTime ? { startTime } : {}),
-    ...(endTime ? { endTime } : {}),
+/** 班级 PK：不给班就用自己的班（老师用默认的班），只给一个班就配一个同年级的对手 */
+export function getClassPk(classes: string[], period: ClassPkPeriod) {
+  return api.get<ClassPk>("rankings/pk", {
+    params: { period, ...(classes.length ? { classes: classes.join(",") } : {}) },
   })
 }
 

apps/web/src/oj/class/components/PkDuel.vue

@@ -0,0 +1,808 @@
+<script setup lang="ts">
+import type { ClassPk, ClassPkCell } from "@oj2/contract"
+import { useThemeVars } from "naive-ui"
+import { classLabel } from "oj/submission/utils"
+import { parseTime } from "utils/functions"
+import { needToTie, pkColor, plateau, shortLabels, tint } from "../utils"
+import PkHist from "./PkHist.vue"
+
+/**
+ * 两个班对决（设计稿「班级 PK」B / 学生 · 两个班 / 手机 · 两个班）：只比两个班都布置过的题，
+ * 谁做对的人多谁赢这道 → 大比分；副比分是一次就对。下面一道一行左右两根条，差得最多的在上；
+ * 再下面每周人均、全班分布。学生看自己班输掉的题，标「再 N 人做对就打平」。
+ */
+const props = defineProps<{ pk: ClassPk; compact: boolean }>()
+
+const theme = useThemeVars()
+
+const left = computed(() => props.pk.classes[0]!)
+const right = computed(() => props.pk.classes[1]!)
+const colors = [pkColor(0), pkColor(1)] as const
+const shorts = computed(() => shortLabels(props.pk))
+const mineIndex = computed(() =>
+  props.pk.classes.findIndex((item) => item.className === props.pk.mine),
+)
+
+function nameOf(index: number) {
+  return index === mineIndex.value ? "你们班" : shorts.value[index]!
+}
+
+type Side = "left" | "right" | "tie"
+
+const rows = computed(() =>
+  props.pk.problems
+    .map((problem) => {
+      const [a, b] = problem.cells as [ClassPkCell, ClassPkCell]
+      const winner: Side = a.best && b.best ? "tie" : a.best ? "left" : "right"
+      const first: Side =
+        a.firstPercent === b.firstPercent
+          ? "tie"
+          : a.firstPercent > b.firstPercent
+            ? "left"
+            : "right"
+      let tie: number | null = null
+      const mine = mineIndex.value
+      if (mine >= 0 && winner !== "tie" && winner !== (mine === 0 ? "left" : "right")) {
+        const own = mine === 0 ? a : b
+        const other = mine === 0 ? b : a
+        tie = needToTie(own, props.pk.classes[mine]!.members, other.percent)
+      }
+      return { problem, a, b, winner, first, gap: Math.abs(a.percent - b.percent), tie }
+    })
+    .sort((x, y) => y.gap - x.gap || x.problem.problemId - y.problem.problemId),
+)
+
+const score = computed(() => {
+  const count = (key: "winner" | "first", side: Side) =>
+    rows.value.filter((row) => row[key] === side).length
+  return {
+    left: count("winner", "left"),
+    right: count("winner", "right"),
+    tie: count("winner", "tie"),
+    firstLeft: count("first", "left"),
+    firstRight: count("first", "right"),
+  }
+})
+
+const steadier = computed(() => {
+  const { firstLeft, firstRight } = score.value
+  if (firstLeft === firstRight) return "两个班一样稳"
+  return `${nameOf(firstLeft > firstRight ? 0 : 1)}更稳`
+})
+
+/** 只有一个班布置过的题：不比，列几道名字 */
+const soloText = computed(() => {
+  const { solo } = props.pk
+  if (!solo.length) return ""
+  const names = solo.slice(0, 2).map((item) => `「${item.title}」`)
+  const owners = new Set(solo.map((item) => item.className))
+  const who =
+    owners.size === 1
+      ? `只有${nameOf(props.pk.classes.findIndex((item) => item.className === solo[0]!.className))}做过的`
+      : "只有一个班做过的"
+  return `${who} ${solo.length} 道不比：${names.join("、")}${solo.length > 2 ? " 等" : ""}`
+})
+
+const SHOW_MOBILE = 7
+const expanded = ref(false)
+const shownRows = computed(() =>
+  props.compact && !expanded.value ? rows.value.slice(0, SHOW_MOBILE) : rows.value,
+)
+
+/** 每周人均：最近 8 周，两班并排的柱 */
+const weeks = computed(() => {
+  const from = Math.max(0, props.pk.weeks.length - 8)
+  const list = props.pk.weeks.slice(from).map((week, k) => ({
+    label: parseTime(week, "M月D日"),
+    values: [left.value.weekly[from + k] ?? 0, right.value.weekly[from + k] ?? 0],
+  }))
+  const max = Math.max(1, ...list.flatMap((week) => week.values))
+  return { list, max }
+})
+
+const plateaus = computed(() => [
+  plateau(left.value.distribution),
+  plateau(right.value.distribution),
+])
+
+const tab = ref<"weekly" | "dist">("weekly")
+</script>
+
+<template>
+  <div class="duel" :class="{ compact }">
+    <div
+      class="score"
+      :style="{
+        background: `linear-gradient(90deg, ${tint(colors[0], 0.12)} 0%, transparent 38%, transparent 62%, ${tint(colors[1], 0.12)} 100%)`,
+      }"
+    >
+      <div
+        v-for="(item, index) in [left, right]"
+        :key="item.className"
+        class="side"
+        :class="{ end: index === 1 }"
+      >
+        <span class="side-name" :style="{ color: colors[index] }">
+          <template v-if="index === mineIndex">
+            你们班<small>{{ compact ? shorts[index] : classLabel(item.className) }}</small>
+          </template>
+          <template v-else>{{ compact ? shorts[index] : classLabel(item.className) }}</template>
+        </span>
+        <span class="side-sub">
+          {{ item.members }} 人 · 人均做对 <b>{{ item.perCapita }}</b>
+          <template v-if="!compact && item.firstPercent !== null">
+            · 一次就对 {{ item.firstPercent }}%</template
+          >
+        </span>
+      </div>
+      <div class="mid">
+        <span class="muted">两个班都做过的 {{ rows.length }} 道题 · 谁做对的人多谁赢这道</span>
+        <span class="big">
+          <b :style="{ color: colors[0] }">{{ score.left }}</b>
+          <i>:</i>
+          <b :style="{ color: colors[1] }">{{ score.right }}</b>
+        </span>
+        <span class="mid-sub">
+          平 {{ score.tie }} 道 · 比一次就对：
+          <b :style="{ color: colors[0] }">{{ score.firstLeft }}</b> :
+          <b :style="{ color: colors[1] }">{{ score.firstRight }}</b
+          >，{{ steadier }}
+        </span>
+      </div>
+    </div>
+
+    <div class="card">
+      <div class="card-head">
+        <b>同一批题</b>
+        <span class="muted">
+          条 = 全班做对的人占几成<template v-if="!compact">
+            · 皇冠 = 这道赢了 · 按两班差距从大到小</template
+          >
+        </span>
+        <div class="spacer" />
+        <span v-if="soloText && !compact" class="muted">{{ soloText }}</span>
+      </div>
+
+      <template v-if="!compact">
+        <div v-for="row in shownRows" :key="row.problem.problemId" class="row">
+          <span class="info left">
+            <span class="value" :class="{ win: row.winner === 'left' }">
+              <svg
+                v-if="row.winner === 'left'"
+                class="crown"
+                viewBox="0 0 24 24"
+                aria-label="这道赢了"
+              >
+                <path d="M3 8l4.5 4L12 5l4.5 7L21 8l-2 11H5z" />
+              </svg>
+              {{ row.a.percent }}%
+            </span>
+            <span class="sub">
+              {{ row.a.solved }}/{{ left.members }} 人 · 一次就对 {{ row.a.firstPercent }}%
+            </span>
+          </span>
+          <span class="bar-box left">
+            <span
+              class="bar"
+              :style="{
+                width: `${row.a.percent}%`,
+                background: colors[0],
+                opacity: row.winner === 'right' ? 0.45 : 1,
+              }"
+            />
+          </span>
+          <span class="title">
+            <router-link class="ell" :to="`/problem/${row.problem.displayId}`">{{
+              row.problem.title
+            }}</router-link>
+            <span class="tags">
+              <span class="muted">#{{ row.problem.displayId }}</span>
+              <span v-if="row.winner === 'tie'" class="muted">平</span>
+              <span v-else-if="row === rows[0] && row.gap > 0" class="most">差得最多</span>
+              <span v-if="row.tie !== null" class="tie" :class="{ close: row.tie <= 2 }">
+                再 {{ row.tie }} 人做对就打平
+              </span>
+            </span>
+          </span>
+          <span class="bar-box">
+            <span
+              class="bar"
+              :style="{
+                width: `${row.b.percent}%`,
+                background: colors[1],
+                opacity: row.winner === 'left' ? 0.45 : 1,
+              }"
+            />
+          </span>
+          <span class="info">
+            <span class="value" :class="{ win: row.winner === 'right' }">
+              {{ row.b.percent }}%
+              <svg
+                v-if="row.winner === 'right'"
+                class="crown"
+                viewBox="0 0 24 24"
+                aria-label="这道赢了"
+              >
+                <path d="M3 8l4.5 4L12 5l4.5 7L21 8l-2 11H5z" />
+              </svg>
+            </span>
+            <span class="sub">
+              {{ row.b.solved }}/{{ right.members }} 人 · 一次就对 {{ row.b.firstPercent }}%
+            </span>
+          </span>
+        </div>
+      </template>
+
+      <template v-else>
+        <div v-for="row in shownRows" :key="row.problem.problemId" class="m-row">
+          <div class="m-title">
+            <router-link class="ell" :to="`/problem/${row.problem.displayId}`">{{
+              row.problem.title
+            }}</router-link>
+            <span v-if="row.tie !== null" class="tie" :class="{ close: row.tie <= 2 }"
+              >再 {{ row.tie }} 人就平</span
+            >
+            <span v-else-if="row.winner === 'tie'" class="muted">平</span>
+          </div>
+          <div v-for="(cell, index) in [row.a, row.b]" :key="index" class="m-line">
+            <span class="m-name" :style="{ color: colors[index] }">{{ shorts[index] }}</span>
+            <span class="bar-box">
+              <span
+                class="bar"
+                :style="{
+                  width: `${cell.percent}%`,
+                  background: colors[index],
+                  opacity:
+                    row.winner !== 'tie' && row.winner !== (index === 0 ? 'left' : 'right')
+                      ? 0.45
+                      : 1,
+                }"
+              />
+            </span>
+            <span class="m-value" :class="{ win: cell.best && row.winner !== 'tie' }"
+              >{{ cell.percent }}%</span
+            >
+            <svg
+              v-if="cell.best && row.winner !== 'tie'"
+              class="crown"
+              viewBox="0 0 24 24"
+              aria-label="这道赢了"
+            >
+              <path d="M3 8l4.5 4L12 5l4.5 7L21 8l-2 11H5z" />
+            </svg>
+            <span v-else class="crown" />
+          </div>
+        </div>
+        <button v-if="rows.length > SHOW_MOBILE" class="more" @click="expanded = !expanded">
+          {{ expanded ? "收起" : `再看 ${rows.length - SHOW_MOBILE} 道 ›` }}
+        </button>
+      </template>
+    </div>
+
+    <div class="bottom" :class="{ compact }">
+      <div v-if="compact" class="tabs" role="tablist">
+        <button :class="{ on: tab === 'weekly' }" role="tab" @click="tab = 'weekly'">
+          每周人均
+        </button>
+        <button :class="{ on: tab === 'dist' }" role="tab" @click="tab = 'dist'">全班分布</button>
+      </div>
+      <div v-if="!compact || tab === 'weekly'" class="card pad">
+        <div v-if="!compact" class="card-title">
+          <b>每周人均新做对</b><span class="muted">这学期，最近 {{ weeks.list.length }} 周</span>
+        </div>
+        <div class="weeks">
+          <div v-for="week in weeks.list" :key="week.label" class="week">
+            <div class="pair">
+              <div v-for="(value, index) in week.values" :key="index" class="bar-col">
+                <span class="v" :style="{ color: colors[index] }">{{ value }}</span>
+                <span
+                  class="wbar"
+                  :style="{
+                    height: `${Math.max(2, (value / weeks.max) * (compact ? 80 : 110))}px`,
+                    background: colors[index],
+                  }"
+                />
+              </div>
+            </div>
+            <span class="axis">{{ week.label }}</span>
+          </div>
+        </div>
+      </div>
+      <div v-if="!compact || tab === 'dist'" class="card pad dist">
+        <div v-if="!compact" class="card-title">
+          <b>全班分布</b><span class="muted">一根柱一档，横轴是做对几道 · 虚线是中间那位</span>
+        </div>
+        <div v-for="(item, index) in [left, right]" :key="item.className" class="dist-one">
+          <span class="dist-name" :style="{ color: colors[index] }">
+            {{ index === mineIndex ? "你们班" : classLabel(item.className) }} · 中间那位
+            {{ item.median }} 道
+            <template v-if="plateaus[index]">
+              · {{ plateaus[index]!.count }} 个人停在 {{ plateaus[index]!.solved }} 道</template
+            >
+          </span>
+          <PkHist :values="item.distribution" :median="item.median" :color="colors[index]" />
+        </div>
+      </div>
+    </div>
+  </div>
+</template>
+
+<style scoped>
+.duel {
+  display: flex;
+  flex-direction: column;
+  gap: 14px;
+}
+
+.score {
+  padding: 18px 28px;
+  border: 1px solid v-bind("theme.borderColor");
+  border-radius: 6px;
+  display: grid;
+  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
+  align-items: center;
+  gap: 24px;
+}
+
+.side {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  grid-row: 1;
+  grid-column: 1;
+}
+
+.side.end {
+  grid-column: 3;
+  align-items: flex-end;
+  text-align: right;
+}
+
+.side-name {
+  font-size: 22px;
+  font-weight: 800;
+  display: flex;
+  align-items: baseline;
+  gap: 8px;
+}
+
+.side-name small {
+  font-size: 14px;
+  font-weight: 600;
+  color: v-bind("theme.textColor3");
+}
+
+.side-sub {
+  font-size: 13px;
+  color: v-bind("theme.textColor2");
+}
+
+.side-sub b {
+  font-size: 15px;
+  font-variant-numeric: tabular-nums;
+}
+
+.mid {
+  grid-row: 1;
+  grid-column: 2;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 2px;
+  text-align: center;
+}
+
+.big {
+  display: flex;
+  align-items: center;
+  gap: 18px;
+  line-height: 1.05;
+}
+
+.big b {
+  font-size: 52px;
+  font-weight: 800;
+  font-variant-numeric: tabular-nums;
+}
+
+.big i {
+  font-style: normal;
+  font-size: 28px;
+  font-weight: 700;
+  color: v-bind("theme.textColor3");
+}
+
+.mid-sub {
+  font-size: 13px;
+  color: v-bind("theme.textColor2");
+}
+
+.muted {
+  font-size: 12px;
+  font-weight: 400;
+  color: v-bind("theme.textColor3");
+}
+
+.card {
+  border: 1px solid v-bind("theme.borderColor");
+  border-radius: 6px;
+  background: v-bind("theme.cardColor");
+  padding: 12px 16px 4px;
+  min-width: 0;
+}
+
+.card.pad {
+  padding: 12px 16px;
+}
+
+.card-head {
+  display: flex;
+  align-items: baseline;
+  flex-wrap: wrap;
+  gap: 4px 8px;
+  padding-bottom: 6px;
+  border-bottom: 1px solid v-bind("theme.dividerColor");
+}
+
+.card-title {
+  display: flex;
+  align-items: baseline;
+  gap: 8px;
+  margin-bottom: 8px;
+}
+
+.spacer {
+  flex-grow: 1;
+}
+
+.row {
+  min-height: 44px;
+  display: grid;
+  grid-template-columns: 168px minmax(0, 1fr) 210px minmax(0, 1fr) 168px;
+  align-items: center;
+  gap: 12px;
+  border-bottom: 1px solid v-bind("theme.dividerColor");
+}
+
+.row:last-child {
+  border-bottom: 0;
+}
+
+.info {
+  display: flex;
+  flex-direction: column;
+}
+
+.info.left {
+  align-items: flex-end;
+}
+
+.value {
+  display: flex;
+  align-items: center;
+  gap: 4px;
+  font-size: 14px;
+  font-weight: 700;
+  font-variant-numeric: tabular-nums;
+  color: v-bind("theme.textColor3");
+}
+
+.value.win {
+  color: v-bind("theme.textColor1");
+}
+
+.sub {
+  font-size: 11px;
+  color: v-bind("theme.textColor3");
+  font-variant-numeric: tabular-nums;
+}
+
+.crown {
+  width: 14px;
+  height: 14px;
+  flex-shrink: 0;
+  fill: #c58b00;
+  stroke: #c58b00;
+  stroke-width: 1.5;
+  stroke-linejoin: round;
+}
+
+.bar-box {
+  height: 16px;
+  display: flex;
+  background: v-bind("theme.actionColor");
+  border-radius: 3px;
+  overflow: hidden;
+}
+
+.bar-box.left {
+  justify-content: flex-end;
+}
+
+.bar {
+  height: 100%;
+}
+
+.title {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 1px;
+  min-width: 0;
+}
+
+.title a,
+.m-title a {
+  max-width: 100%;
+  font-size: 13px;
+  font-weight: 600;
+  color: v-bind("theme.textColor1");
+  text-decoration: none;
+}
+
+.title a:hover,
+.m-title a:hover {
+  color: v-bind("theme.primaryColor");
+}
+
+.ell {
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.tags {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  font-size: 11px;
+}
+
+.tags .muted {
+  font-size: 11px;
+}
+
+.most {
+  font-size: 11px;
+  font-weight: 600;
+  color: #b54708;
+}
+
+.tie {
+  font-size: 11px;
+  font-weight: 600;
+  white-space: nowrap;
+  color: v-bind("theme.textColor3");
+}
+
+.tie.close {
+  color: #18a058;
+  background: rgba(24, 160, 88, 0.12);
+  border-radius: 3px;
+  padding: 0 5px;
+}
+
+.bottom {
+  display: flex;
+  gap: 16px;
+}
+
+.bottom > .card {
+  flex: 1;
+}
+
+.weeks {
+  display: flex;
+  gap: 4px;
+  border-bottom: 1px solid v-bind("theme.dividerColor");
+}
+
+.week {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 4px;
+}
+
+.pair {
+  height: 130px;
+  display: flex;
+  align-items: flex-end;
+  gap: 4px;
+}
+
+.bar-col {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 2px;
+}
+
+.v {
+  font-size: 11px;
+  font-weight: 600;
+  font-variant-numeric: tabular-nums;
+}
+
+.wbar {
+  width: 18px;
+  border-radius: 3px 3px 0 0;
+}
+
+.axis {
+  font-size: 11px;
+  color: v-bind("theme.textColor3");
+  white-space: nowrap;
+}
+
+.dist {
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
+}
+
+.dist-one {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+}
+
+.dist-name {
+  font-size: 12px;
+  font-weight: 600;
+}
+
+/* ---------- 手机 ---------- */
+.compact .score {
+  padding: 12px;
+  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
+  gap: 6px;
+}
+
+.compact .side {
+  grid-row: 1;
+}
+
+.compact .side.end {
+  grid-column: 2;
+}
+
+.compact .side-name {
+  font-size: 15px;
+}
+
+.compact .side-sub {
+  font-size: 12px;
+}
+
+.compact .mid {
+  grid-row: 2;
+  grid-column: 1 / 3;
+}
+
+.compact .big b {
+  font-size: 44px;
+}
+
+.compact .mid-sub {
+  font-size: 12px;
+}
+
+.compact .card {
+  padding: 10px 12px 2px;
+}
+
+.m-row {
+  padding: 8px 0;
+  border-bottom: 1px solid v-bind("theme.dividerColor");
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+}
+
+.m-title {
+  display: flex;
+  align-items: baseline;
+  gap: 6px;
+}
+
+.m-title a {
+  flex: 1;
+  min-width: 0;
+}
+
+.m-line {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+
+.m-line .bar-box {
+  flex: 1;
+  height: 12px;
+}
+
+.m-name {
+  width: 36px;
+  font-size: 12px;
+  font-weight: 600;
+}
+
+.m-value {
+  width: 40px;
+  text-align: right;
+  font-size: 13px;
+  font-variant-numeric: tabular-nums;
+}
+
+.m-value.win {
+  font-weight: 700;
+}
+
+.m-line .crown {
+  width: 14px;
+  height: 14px;
+}
+
+.more {
+  width: 100%;
+  height: 40px;
+  border: 0;
+  background: none;
+  font: inherit;
+  font-size: 13px;
+  color: v-bind("theme.primaryColor");
+  cursor: pointer;
+}
+
+.bottom.compact {
+  flex-direction: column;
+  gap: 0;
+  border: 1px solid v-bind("theme.borderColor");
+  border-radius: 6px;
+  padding: 0 12px 12px;
+}
+
+.bottom.compact > .card {
+  border: 0;
+  padding: 10px 0 0;
+}
+
+.tabs {
+  display: flex;
+  gap: 18px;
+  border-bottom: 1px solid v-bind("theme.dividerColor");
+}
+
+.tabs button {
+  height: 34px;
+  padding: 0;
+  border: 0;
+  background: none;
+  font: inherit;
+  font-size: 14px;
+  color: v-bind("theme.textColor2");
+  cursor: pointer;
+}
+
+.tabs button.on {
+  color: #18a058;
+  font-weight: 600;
+  box-shadow: inset 0 -2px 0 #18a058;
+}
+
+.compact .pair {
+  height: 100px;
+  gap: 2px;
+}
+
+.compact .wbar {
+  width: 12px;
+}
+
+.compact .axis {
+  font-size: 10px;
+}
+</style>

apps/web/src/oj/class/components/PkGrid.vue

@@ -0,0 +1,625 @@
+<script setup lang="ts">
+import type { ClassPk } from "@oj2/contract"
+import { useThemeVars } from "naive-ui"
+import { classLabel } from "oj/submission/utils"
+import { useRankPalette } from "oj/rank/palette"
+import { needToTie, pkColor, shortLabels, tint } from "../utils"
+import PkRace from "./PkRace.vue"
+
+/**
+ * 三个班以上（设计稿「班级 PK」C / 学生 · 三个班 / 手机 · 三个班以上）：题目对照格，一行
+ * 一道题、一格一个班，越深做对的人越多，皇冠 = 这道做得最好（一样多都算）。右边谁领先的题多、
+ * 一句话（学生：离领先最近的那道；老师：差得最多的那道）、赛跑。
+ */
+const props = defineProps<{ pk: ClassPk; compact: boolean }>()
+
+const theme = useThemeVars()
+const palette = useRankPalette()
+
+const shorts = computed(() => shortLabels(props.pk))
+const mineIndex = computed(() =>
+  props.pk.classes.findIndex((item) => item.className === props.pk.mine),
+)
+
+const rows = computed(() =>
+  props.pk.problems.map((problem) => {
+    const top = Math.max(...problem.cells.map((cell) => cell?.percent ?? -1))
+    const winner = problem.cells.findIndex((cell) => cell?.best)
+    const own = mineIndex.value >= 0 ? problem.cells[mineIndex.value] : null
+    const tie =
+      own && !own.best ? needToTie(own, props.pk.classes[mineIndex.value]!.members, top) : null
+    return {
+      problem,
+      winner,
+      tie,
+      cells: problem.cells.map((cell, index) => {
+        if (!cell) return null
+        // 做对比例 45% 以下最浅，100% 最深；深到压白字时字换白
+        const alpha = Math.max(0.1, Math.min(0.85, ((cell.percent - 45) / 55) * 0.85))
+        return {
+          ...cell,
+          background: tint(pkColor(index), alpha),
+          dark: alpha > 0.5,
+          hint: `${props.pk.classes[index]!.className.slice(2)}班：做对 ${cell.solved}/${props.pk.classes[index]!.members} 人、交了 ${cell.submissions} 次、一次就对 ${cell.firstPercent}%`,
+        }
+      }),
+    }
+  }),
+)
+
+const ranking = computed(() =>
+  props.pk.classes
+    .map((item, index) => ({ item, index }))
+    .sort((a, b) => b.item.lead - a.item.lead || b.item.perCapita - a.item.perCapita),
+)
+
+/** 右边那一句：学生看离领先最近的那道，老师看差得最多的那道 */
+const insight = computed(() => {
+  if (mineIndex.value >= 0) {
+    const close = rows.value.filter((row) => row.tie !== null).sort((a, b) => a.tie! - b.tie!)[0]
+    if (!close) return { mine: true, text: "同一批题你们班都做得最好" }
+    return {
+      mine: true,
+      text: `离领先最近：「${close.problem.title}」再 ${close.tie} 人做对就和${shorts.value[close.winner]}打平`,
+    }
+  }
+  let worst: { title: string; low: number; lowIndex: number; others: number } | null = null
+  for (const row of rows.value) {
+    const present = row.cells
+      .map((cell, index) => (cell ? { percent: cell.percent, index } : null))
+      .filter((cell): cell is { percent: number; index: number } => !!cell)
+      .sort((a, b) => a.percent - b.percent)
+    const gap = present[1]!.percent - present[0]!.percent
+    if (!worst || gap > worst.others - worst.low)
+      worst = {
+        title: row.problem.title,
+        low: present[0]!.percent,
+        lowIndex: present[0]!.index,
+        others: present[1]!.percent,
+      }
+  }
+  if (!worst || worst.others === worst.low) return null
+  return {
+    mine: false,
+    text: `差得最多的是「${worst.title}」：${shorts.value[worst.lowIndex]}只有 ${worst.low}% 做对，别的班都在 ${worst.others}% 以上`,
+  }
+})
+
+const SHOW_MOBILE = 8
+const expanded = ref(false)
+const shownRows = computed(() =>
+  props.compact && !expanded.value ? rows.value.slice(0, SHOW_MOBILE) : rows.value,
+)
+const soloCount = computed(() => props.pk.solo.length)
+
+const tab = ref<"race" | "lead">("race")
+const medal = (index: number) => palette.value.medal[index]
+</script>
+
+<template>
+  <div class="grid-pk" :class="{ compact }">
+    <div class="card table">
+      <div class="card-title">
+        <b>同一批题 · 一格一个班</b>
+        <span class="muted">
+          格子里是全班做对的人占几成，越深越多<template v-if="!compact">
+            · 皇冠 = 这道题做得最好的班（一样多就都算）</template
+          >
+        </span>
+      </div>
+      <div class="line heads">
+        <span v-if="!compact" class="name muted">至少两个班布置过的 {{ rows.length }} 道</span>
+        <span
+          v-for="(item, index) in pk.classes"
+          :key="item.className"
+          class="head"
+          :class="{ mine: index === mineIndex }"
+          :style="{ background: tint(pkColor(index), 0.1) }"
+        >
+          <span class="head-name" :style="{ color: pkColor(index) }">
+            {{ compact ? shorts[index] : classLabel(item.className) }}
+            <span v-if="index === mineIndex" class="mine-tag">{{
+              compact ? "你们" : "你们班"
+            }}</span>
+          </span>
+          <span class="head-lead">
+            <span v-if="!compact" class="muted">领先</span>
+            <b :style="{ color: pkColor(index) }">{{ item.lead }}</b>
+            <span class="muted">{{ compact ? "道领先" : "道" }}</span>
+          </span>
+          <span v-if="!compact" class="muted per">人均做对 {{ item.perCapita }}</span>
+        </span>
+      </div>
+      <div
+        v-for="row in shownRows"
+        :key="row.problem.problemId"
+        class="line"
+        :class="{ stacked: compact }"
+      >
+        <span class="name">
+          <span v-if="!compact" class="muted id">#{{ row.problem.displayId }}</span>
+          <router-link class="ell" :to="`/problem/${row.problem.displayId}`">{{
+            row.problem.title
+          }}</router-link>
+          <span v-if="row.tie !== null" class="tie" :class="{ close: row.tie <= 2 }"
+            >再 {{ row.tie }} 人就平</span
+          >
+        </span>
+        <div class="cells">
+          <template v-for="(cell, index) in row.cells" :key="index">
+            <span v-if="!cell" class="cell none">{{ compact ? "—" : "没布置" }}</span>
+            <span
+              v-else
+              class="cell"
+              :class="{ best: cell.best, dark: cell.dark, mine: index === mineIndex }"
+              :style="{ background: cell.background }"
+              :title="cell.hint"
+            >
+              <svg v-if="cell.best" class="crown" viewBox="0 0 24 24" aria-label="这道做得最好">
+                <path d="M3 8l4.5 4L12 5l4.5 7L21 8l-2 11H5z" />
+              </svg>
+              <b>{{ cell.percent }}{{ compact ? "" : "%" }}</b>
+              <span v-if="!compact" class="first">一次 {{ cell.firstPercent }}%</span>
+            </span>
+          </template>
+        </div>
+      </div>
+      <button
+        v-if="compact && rows.length > SHOW_MOBILE"
+        class="more"
+        @click="expanded = !expanded"
+      >
+        {{ expanded ? "收起" : `再看 ${rows.length - SHOW_MOBILE} 道 ›` }}
+      </button>
+      <span v-if="!compact && soloCount" class="muted foot">
+        只有一个班做过的 {{ soloCount }} 道不在格子里 · 鼠标放到格子上看做对几个人、交了几次
+      </span>
+    </div>
+
+    <div class="side" :class="{ compact }">
+      <div v-if="compact" class="tabs" role="tablist">
+        <button :class="{ on: tab === 'race' }" role="tab" @click="tab = 'race'">赛跑</button>
+        <button :class="{ on: tab === 'lead' }" role="tab" @click="tab = 'lead'">
+          谁领先的题多
+        </button>
+      </div>
+      <div v-if="!compact || tab === 'lead'" class="card pad">
+        <div v-if="!compact" class="card-title">
+          <b>谁领先的题多</b><span class="muted">同一批题里</span>
+        </div>
+        <div
+          v-for="({ item, index }, place) in ranking"
+          :key="item.className"
+          class="lead-row"
+          :class="{ mine: index === mineIndex }"
+        >
+          <span
+            class="medal"
+            :style="
+              medal(place)
+                ? { color: medal(place)!.color, background: medal(place)!.background }
+                : undefined
+            "
+            >{{ place + 1 }}</span
+          >
+          <span class="lead-name" :style="{ color: pkColor(index) }">
+            {{ classLabel(item.className) }}
+            <span v-if="index === mineIndex" class="mine-tag">你们班</span>
+          </span>
+          <span
+            ><b class="num">{{ item.lead }}</b
+            ><span class="muted"> 道领先</span></span
+          >
+        </div>
+        <div v-if="insight" class="insight" :class="{ mine: insight.mine }">{{ insight.text }}</div>
+      </div>
+      <div v-if="!compact || tab === 'race'" class="card pad">
+        <div v-if="!compact" class="card-title">
+          <b>赛跑</b><span class="muted">这学期累计人均做对</span>
+        </div>
+        <PkRace :pk="pk" :width="420" :height="compact ? 220 : 230" />
+      </div>
+    </div>
+  </div>
+</template>
+
+<style scoped>
+.grid-pk {
+  display: flex;
+  gap: 16px;
+  align-items: flex-start;
+}
+
+.grid-pk.compact {
+  flex-direction: column;
+  align-items: stretch;
+  gap: 10px;
+}
+
+.card {
+  border: 1px solid v-bind("theme.borderColor");
+  border-radius: 6px;
+  background: v-bind("theme.cardColor");
+  min-width: 0;
+}
+
+.table {
+  flex: 1.75;
+  padding: 12px 16px;
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+}
+
+.pad {
+  padding: 12px 16px;
+}
+
+.card-title {
+  display: flex;
+  align-items: baseline;
+  flex-wrap: wrap;
+  gap: 4px 8px;
+}
+
+.muted {
+  font-size: 12px;
+  font-weight: 400;
+  color: v-bind("theme.textColor3");
+}
+
+.line {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  min-height: 40px;
+}
+
+.line.heads {
+  align-items: stretch;
+}
+
+.name {
+  width: 290px;
+  flex-shrink: 0;
+  display: flex;
+  align-items: baseline;
+  gap: 6px;
+  min-width: 0;
+}
+
+.heads .name {
+  align-items: flex-end;
+  padding-bottom: 6px;
+}
+
+.name a {
+  font-size: 13px;
+  font-weight: 600;
+  color: v-bind("theme.textColor1");
+  text-decoration: none;
+  min-width: 0;
+}
+
+.name a:hover {
+  color: v-bind("theme.primaryColor");
+}
+
+.id {
+  flex-shrink: 0;
+  font-size: 11px;
+}
+
+.ell {
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.head {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 2px;
+  padding: 8px 0;
+  border-radius: 6px;
+}
+
+.head.mine {
+  box-shadow: inset 0 0 0 2px #9fd8b8;
+}
+
+.head-name {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  font-weight: 700;
+}
+
+.head-lead {
+  display: flex;
+  align-items: baseline;
+  gap: 4px;
+  white-space: nowrap;
+}
+
+.per {
+  font-size: 11px;
+  white-space: nowrap;
+}
+
+.head-lead b {
+  font-size: 22px;
+  font-variant-numeric: tabular-nums;
+}
+
+.mine-tag {
+  font-size: 11px;
+  background: rgba(24, 160, 88, 0.12);
+  color: #18a058;
+  border-radius: 3px;
+  padding: 0 5px;
+  height: 16px;
+  display: inline-flex;
+  align-items: center;
+  font-weight: 600;
+  white-space: nowrap;
+}
+
+.cells {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  gap: 6px;
+}
+
+.heads .head,
+.cells .cell {
+  flex: 1;
+}
+
+.cell {
+  min-width: 0;
+  height: 34px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 6px;
+  border-radius: 4px;
+  color: v-bind("theme.textColor1");
+  font-variant-numeric: tabular-nums;
+}
+
+.cell.dark {
+  color: #ffffff;
+}
+
+.cell.best {
+  box-shadow: inset 0 0 0 2px #c58b00;
+}
+
+.cell b {
+  font-size: 14px;
+}
+
+.first {
+  font-size: 11px;
+  opacity: 0.85;
+}
+
+.cell.none {
+  font-size: 12px;
+  color: v-bind("theme.textColorDisabled");
+  background: repeating-linear-gradient(
+    135deg,
+    v-bind("theme.actionColor") 0 6px,
+    v-bind("theme.hoverColor") 6px 12px
+  );
+}
+
+.crown {
+  width: 12px;
+  height: 12px;
+  flex-shrink: 0;
+  fill: #c58b00;
+  stroke: #c58b00;
+  stroke-width: 1.5;
+  stroke-linejoin: round;
+}
+
+.cell.dark .crown {
+  fill: #ffffff;
+  stroke: #ffffff;
+}
+
+.tie {
+  flex-shrink: 0;
+  font-size: 11px;
+  font-weight: 600;
+  white-space: nowrap;
+  color: v-bind("theme.textColor3");
+}
+
+.tie.close {
+  color: #18a058;
+  background: rgba(24, 160, 88, 0.12);
+  border-radius: 3px;
+  padding: 0 5px;
+}
+
+.foot {
+  padding-top: 4px;
+}
+
+.side {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 16px;
+}
+
+.lead-row {
+  height: 34px;
+  display: flex;
+  align-items: center;
+  gap: 10px;
+}
+
+.lead-row.mine {
+  background: rgba(24, 160, 88, 0.08);
+  border-radius: 6px;
+  padding: 0 6px;
+  margin: 0 -6px;
+}
+
+.medal {
+  width: 26px;
+  height: 26px;
+  border-radius: 13px;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  font-weight: 700;
+  font-size: 13px;
+  flex-shrink: 0;
+  color: v-bind("theme.textColor2");
+}
+
+.lead-name {
+  flex: 1;
+  font-weight: 600;
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+
+.num {
+  font-size: 16px;
+  font-variant-numeric: tabular-nums;
+}
+
+.insight {
+  margin-top: 8px;
+  font-size: 13px;
+  color: v-bind("theme.textColor2");
+  padding: 8px 10px;
+  background: v-bind("theme.actionColor");
+  border-radius: 6px;
+}
+
+.insight.mine {
+  background: transparent;
+  border: 1px dashed #9fd8b8;
+  color: #18a058;
+  font-weight: 600;
+}
+
+.more {
+  width: 100%;
+  height: 40px;
+  border: 0;
+  background: none;
+  font: inherit;
+  font-size: 13px;
+  color: v-bind("theme.primaryColor");
+  cursor: pointer;
+}
+
+/* ---------- 手机 ---------- */
+.compact .table {
+  padding: 10px 12px 2px;
+}
+
+.compact .line.heads {
+  min-height: 0;
+  padding-top: 4px;
+}
+
+.compact .head {
+  padding: 6px 0;
+}
+
+.compact .head-name {
+  font-size: 12px;
+  flex-direction: column;
+  gap: 0;
+}
+
+.compact .per {
+  font-size: 11px;
+  white-space: nowrap;
+}
+
+.head-lead b {
+  font-size: 20px;
+}
+
+.line.stacked {
+  flex-direction: column;
+  align-items: stretch;
+  gap: 4px;
+  padding: 6px 0;
+  border-bottom: 1px solid v-bind("theme.dividerColor");
+}
+
+.line.stacked .name {
+  width: auto;
+}
+
+.compact .cells {
+  gap: 4px;
+}
+
+.compact .cell {
+  height: 28px;
+  gap: 2px;
+  font-size: 12px;
+}
+
+.compact .cell b {
+  font-size: 12px;
+}
+
+.compact .crown {
+  width: 10px;
+  height: 10px;
+}
+
+.side.compact {
+  gap: 0;
+  border: 1px solid v-bind("theme.borderColor");
+  border-radius: 6px;
+  padding: 0 12px 12px;
+}
+
+.side.compact .card {
+  border: 0;
+  padding: 10px 0 0;
+}
+
+.tabs {
+  display: flex;
+  gap: 18px;
+  border-bottom: 1px solid v-bind("theme.dividerColor");
+}
+
+.tabs button {
+  height: 34px;
+  padding: 0;
+  border: 0;
+  background: none;
+  font: inherit;
+  font-size: 14px;
+  color: v-bind("theme.textColor2");
+  cursor: pointer;
+}
+
+.tabs button.on {
+  color: #18a058;
+  font-weight: 600;
+  box-shadow: inset 0 -2px 0 #18a058;
+}
+</style>

apps/web/src/oj/class/components/PkHist.vue

@@ -0,0 +1,88 @@
+<script setup lang="ts">
+import { useThemeVars } from "naive-ui"
+
+/**
+ * 全班分布：横轴做对几道（0–30，再多的堆在最右一档），一根柱一档，虚线是中间那位同学。
+ * 人少的档（不到 3 个）淡一点，一眼看到大部分人停在哪。
+ */
+const props = withDefaults(
+  defineProps<{ values: number[]; median: number; color: string; height?: number }>(),
+  { height: 44 },
+)
+
+const theme = useThemeVars()
+
+const CAP = 30
+const WIDTH = 560
+
+const bars = computed(() => {
+  const counts = new Map<number, number>()
+  for (const value of props.values) {
+    const key = Math.min(value, CAP)
+    counts.set(key, (counts.get(key) ?? 0) + 1)
+  }
+  const tallest = Math.max(16, ...counts.values())
+  const width = WIDTH / (CAP + 1)
+  return {
+    width,
+    list: [...counts].map(([value, n]) => {
+      const h = Math.max(2, (props.height * n) / tallest)
+      return { value, n, x: value * width + 0.5, y: props.height - h, h }
+    }),
+    median: (Math.min(props.median, CAP) + 0.5) * width,
+  }
+})
+</script>
+
+<template>
+  <svg
+    class="hist"
+    :viewBox="`0 0 ${WIDTH} ${height + 12}`"
+    role="img"
+    aria-label="全班做对几道的分布"
+  >
+    <line :x1="0" :x2="WIDTH" :y1="height + 0.5" :y2="height + 0.5" :stroke="theme.dividerColor" />
+    <rect
+      v-for="bar in bars.list"
+      :key="bar.value"
+      :x="bar.x"
+      :y="bar.y"
+      :width="bars.width - 1"
+      :height="bar.h"
+      rx="1"
+      :fill="color"
+      :opacity="bar.n >= 3 ? 0.9 : 0.55"
+    >
+      <title>做对 {{ bar.value }}{{ bar.value === CAP ? " 道以上" : " 道" }}：{{ bar.n }} 人</title>
+    </rect>
+    <line
+      :x1="bars.median"
+      :x2="bars.median"
+      y1="0"
+      :y2="height"
+      :stroke="theme.textColor2"
+      stroke-dasharray="2 2"
+    />
+    <text x="0" :y="height + 11" font-size="9" :fill="theme.textColor3">0</text>
+    <text
+      :x="15 * bars.width"
+      :y="height + 11"
+      font-size="9"
+      :fill="theme.textColor3"
+      text-anchor="middle"
+    >
+      15
+    </text>
+    <text :x="WIDTH" :y="height + 11" font-size="9" :fill="theme.textColor3" text-anchor="end">
+      30+
+    </text>
+  </svg>
+</template>
+
+<style scoped>
+.hist {
+  display: block;
+  width: 100%;
+  height: auto;
+}
+</style>

apps/web/src/oj/class/components/PkRace.vue

@@ -0,0 +1,135 @@
+<script setup lang="ts">
+import type { ClassPk } from "@oj2/contract"
+import { useThemeVars } from "naive-ui"
+import { parseTime } from "utils/functions"
+import { pkColor, shortLabels } from "../utils"
+
+/**
+ * 赛跑：每个班这学期累计人均做对，一周一个点，线尾写班名和到现在的人均。
+ * 按 viewBox 等比缩放，放在多宽的格子里都行。
+ */
+const props = withDefaults(defineProps<{ pk: ClassPk; width?: number; height?: number }>(), {
+  width: 700,
+  height: 280,
+})
+
+const theme = useThemeVars()
+
+const PAD = { left: 34, right: 92, top: 10, bottom: 26 }
+
+const series = computed(() =>
+  props.pk.classes.map((item) => {
+    let sum = 0
+    return item.weekly.map((value) => Math.round((sum += value) * 10) / 10)
+  }),
+)
+
+const chart = computed(() => {
+  const inner = {
+    w: props.width - PAD.left - PAD.right,
+    h: props.height - PAD.top - PAD.bottom,
+  }
+  const top = Math.max(1, ...series.value.flat())
+  const step = top > 30 ? 10 : top > 12 ? 6 : top > 5 ? 2 : 1
+  const max = Math.ceil(top / step) * step
+  const count = props.pk.weeks.length
+  const x = (index: number) =>
+    PAD.left + (count > 1 ? (inner.w * index) / (count - 1) : inner.w / 2)
+  const y = (value: number) => PAD.top + inner.h * (1 - value / max)
+
+  const ticks = Array.from({ length: max / step + 1 }, (_, k) => ({
+    value: k * step,
+    y: y(k * step),
+  }))
+  // 周多了横轴字会挤：最多标 8 个，最后一周一定标
+  const every = Math.max(1, Math.ceil(count / 8))
+  const labels = props.pk.weeks
+    .map((week, index) => ({ index, x: x(index), text: parseTime(week, "M月D日") }))
+    .filter(({ index }) => index === count - 1 || (count - 1 - index) % every === 0)
+
+  const labelsShort = shortLabels(props.pk)
+  const lines = series.value.map((points, index) => ({
+    color: pkColor(index),
+    path: points.map((value, k) => `${x(k).toFixed(1)},${y(value).toFixed(1)}`).join(" "),
+    dots: points.map((value, k) => ({ cx: x(k), cy: y(value) })),
+    end: { y: y(points.at(-1) ?? 0), text: `${labelsShort[index]} ${points.at(-1) ?? 0}` },
+  }))
+  // 线尾的字别叠在一起：按高低排，挨得太近的往下推
+  const ends = lines.map((line, index) => ({ index, y: line.end.y })).sort((a, b) => a.y - b.y)
+  for (let k = 1; k < ends.length; k++)
+    if (ends[k]!.y - ends[k - 1]!.y < 14) ends[k]!.y = ends[k - 1]!.y + 14
+  for (const end of ends) lines[end.index]!.end.y = end.y
+
+  return { ticks, labels, lines, endX: x(count - 1) + 10, right: PAD.left + inner.w }
+})
+</script>
+
+<template>
+  <svg
+    class="race"
+    :viewBox="`0 0 ${width} ${height}`"
+    role="img"
+    aria-label="各班这学期累计人均做对，一周一个点"
+  >
+    <g v-for="tick in chart.ticks" :key="tick.value">
+      <line
+        :x1="PAD.left"
+        :x2="chart.right"
+        :y1="tick.y"
+        :y2="tick.y"
+        :stroke="theme.dividerColor"
+      />
+      <text
+        :x="PAD.left - 8"
+        :y="tick.y + 4"
+        font-size="11"
+        :fill="theme.textColor3"
+        text-anchor="end"
+      >
+        {{ tick.value }}
+      </text>
+    </g>
+    <text
+      v-for="label in chart.labels"
+      :key="label.index"
+      :x="label.x"
+      :y="height - 6"
+      font-size="11"
+      :fill="theme.textColor3"
+      text-anchor="middle"
+    >
+      {{ label.text }}
+    </text>
+    <g v-for="(line, index) in chart.lines" :key="index">
+      <polyline
+        :points="line.path"
+        fill="none"
+        :stroke="line.color"
+        stroke-width="2.5"
+        stroke-linejoin="round"
+        stroke-linecap="round"
+      />
+      <circle
+        v-for="(dot, k) in line.dots"
+        :key="k"
+        :cx="dot.cx"
+        :cy="dot.cy"
+        r="3.2"
+        :fill="theme.cardColor"
+        :stroke="line.color"
+        stroke-width="2"
+      />
+      <text :x="chart.endX" :y="line.end.y + 4" font-size="12" font-weight="700" :fill="line.color">
+        {{ line.end.text }}
+      </text>
+    </g>
+  </svg>
+</template>
+
+<style scoped>
+.race {
+  display: block;
+  width: 100%;
+  height: auto;
+}
+</style>

apps/web/src/oj/class/utils.ts

@@ -0,0 +1,59 @@
+import type { ClassPk, ClassPkCell } from "@oj2/contract"
+import { classLabel } from "oj/submission/utils"
+
+/**
+ * 每个班一种颜色，按选班的顺序给。蓝 / 橙打头：两个班对决时最常见，这两个色盲也分得开；
+ * 后面几个亮度错开，对照格的深浅才看得出来。
+ */
+const COLORS = [
+  "#2f6fd0",
+  "#e0702f",
+  "#18a058",
+  "#8e5bd0",
+  "#b8901a",
+  "#d0457a",
+  "#0f8f9f",
+  "#5f6b7a",
+]
+
+export function pkColor(index: number) {
+  return COLORS[index % COLORS.length]!
+}
+
+/** 颜色加透明度：对照格按做对比例取深浅，比分卡两头的底色也用它（暗色下一样能用） */
+export function tint(hex: string, alpha: number) {
+  const r = parseInt(hex.slice(1, 3), 16)
+  const g = parseInt(hex.slice(3, 5), 16)
+  const b = parseInt(hex.slice(5, 7), 16)
+  return `rgba(${r}, ${g}, ${b}, ${alpha})`
+}
+
+/** 同一个年级的几个班只说「3班」，跨年级说全名 */
+export function shortLabels(pk: ClassPk) {
+  const grades = new Set(pk.classes.map((item) => item.className.slice(0, 2)))
+  return pk.classes.map((item) =>
+    grades.size === 1 ? `${item.className.slice(2)}班` : classLabel(item.className),
+  )
+}
+
+/**
+ * 你们班再有几个人做对，这道就能和 `target` 打平。比的是显示出来的整数百分比
+ * （后端 `percent` 就是这么比输赢的），所以按同样的取整往上加。
+ */
+export function needToTie(cell: ClassPkCell, members: number, target: number) {
+  let more = 0
+  while (
+    Math.round(((cell.solved + more) / members) * 100) < target &&
+    cell.solved + more < members
+  )
+    more++
+  return more
+}
+
+/** 一档同分人最多、且至少 5 个人，才说「N 个人停在 x 道」 */
+export function plateau(values: number[]) {
+  const counts = new Map<number, number>()
+  for (const value of values) if (value > 0) counts.set(value, (counts.get(value) ?? 0) + 1)
+  const [top] = [...counts].filter(([, n]) => n >= 5).sort((a, b) => b[1] - a[1] || b[0] - a[0])
+  return top ? { solved: top[0], count: top[1] } : null
+}

apps/web/src/oj/rank/components/ClassBattle.vue

@@ -14,7 +14,7 @@ const props = defineProps<{
   teacher?: boolean
   /** 放在手机页签卡里：不要自己的边框和标题 */
   bare?: boolean
-  /** 显示「班级 PK」入口（原来排名页上那个按钮，管理员角色才有） */
+  /** 显示「班级 PK」入口（登录了就有：学生也能比） */
   pk?: boolean
 }>()
 const emit = defineEmits<{ pick: [className: string] }>()
@@ -56,7 +56,12 @@ function shortLabel(className: string) {
   <div class="battle" :class="{ bare }">
     <div class="title">
       <b v-if="!bare">班级对抗</b><span class="muted">人均做对 · 全服 · 点班名看详情</span>
-      <router-link v-if="pk" to="/class" class="pk">班级 PK ›</router-link>
+      <router-link
+        v-if="pk"
+        :to="{ path: '/class', query: mine ? { classes: mine } : {} }"
+        class="pk"
+        >班级 PK ›</router-link
+      >
     </div>
     <div
       v-for="item in shown"

apps/web/src/oj/rank/components/ClassDetailDrawer.vue

@@ -245,7 +245,7 @@ function go(path: string, query: Record<string, string>) {
             <MdPreview v-if="report" class="report" :model-value="report" />
           </section>
 
-          <a v-if="pk" href="#" class="pk" @click.prevent="go('/class', {})"
+          <a v-if="pk" href="#" class="pk" @click.prevent="go('/class', { classes: className! })"
             >和别的班比 → 班级 PK ›</a
           >
         </div>

apps/web/src/oj/rank/list.vue

@@ -480,7 +480,17 @@ async function restore(userId: number) {
               >
                 班级详情 · AI 分析
               </n-button>
-              <n-button size="small" secondary @click="router.push('/class')">班级 PK</n-button>
+              <n-button
+                size="small"
+                secondary
+                @click="
+                  router.push({
+                    path: '/class',
+                    query: classContext ? { classes: classContext } : {},
+                  })
+                "
+                >班级 PK</n-button
+              >
             </div>
             <div class="hidden-list">
               <span class="hidden-title">不计入排名的人</span>
@@ -506,7 +516,7 @@ async function restore(userId: number) {
           :items="battle"
           :mine="classContext"
           :teacher="teacher"
-          :pk="userStore.isAdminRole"
+          :pk="userStore.isAuthed"
           @pick="openDetail"
         />
       </aside>
@@ -560,7 +570,7 @@ async function restore(userId: number) {
           :items="battle"
           :mine="classContext"
           :teacher="teacher"
-          :pk="userStore.isAdminRole"
+          :pk="userStore.isAuthed"
           @pick="openDetail"
         />
         <RankTrend
@@ -586,7 +596,7 @@ async function restore(userId: number) {
       v-model:show="showDetail"
       :class-name="detailClass"
       :teacher="teacher"
-      :pk="userStore.isAdminRole"
+      :pk="userStore.isAuthed"
     />
   </div>
 </template>

apps/web/src/routes.ts

@@ -93,6 +93,7 @@ export const ojs: RouteRecordRaw = {
       path: "class",
       name: "class",
       component: () => import("oj/class/pk.vue"),
+      meta: { requiresAuth: true },
     },
     {
       path: "announcement",

apps/web/src/utils/types.ts

@@ -275,8 +275,6 @@ export type Rank = RankProfile
 /** 本周进步榜：`rank` 是周榜名次，跟存量总榜的名次没有关系 */
 export type { WeeklyRank, WeeklyRankItem } from "@oj2/contract"
 
-export type { ClassComparison } from "@oj2/contract"
-
 /** 班里最近一次一起做的题（课上老师点的那几道），见后端 `/me/class-activity` */
 export type { ClassActivity, ClassActivityProblem, LastVisit } from "@oj2/contract"
 

packages/contract/src/ai.ts

@@ -1,5 +1,7 @@
 import { z } from "zod"
 
+import { classPkPeriodSchema } from "./ranking"
+
 /**
  * 评级。`grade()` 返回 S/A/B/C，`averageGrade()` 在没有可用数据时返回空串 ——
  * 空串是真会下发的值，别把它从这里去掉，前端要按「无评级」处理。
@@ -240,9 +242,10 @@ export const classAnalysisRequestSchema = z.object({
   className: z.string().trim().min(1).max(32),
 })
 
+/** 班级 PK 的 AI 分析同样只传班号和时间段，数字和页面上的是同一份（services/ranking.ts 的 classPk） */
 export const classPkAnalysisRequestSchema = z.object({
-  comparisons: z.array(z.record(z.string(), z.unknown())).min(2),
-  timeRangeLabel: z.string().default("全部时间"),
+  classNames: z.array(z.string().trim().min(1).max(32)).min(2).max(8),
+  period: classPkPeriodSchema,
 })
 
 /**

packages/contract/src/classroom.ts

@@ -3,44 +3,6 @@ import { z } from "zod"
 import { judgeStatusSchema } from "./judge-status"
 import { lessonLanguageSchema as lessonLanguageValueSchema } from "./language"
 
-export const classComparisonSchema = z.object({
-  className: z.string(),
-  userCount: z.number().int(),
-  totalAc: z.number().int(),
-  totalSubmission: z.number().int(),
-  avgAc: z.number(),
-  medianAc: z.number(),
-  q1Ac: z.number(),
-  q3Ac: z.number(),
-  iqr: z.number(),
-  stdDev: z.number(),
-  top10Avg: z.number(),
-  middle80Avg: z.number(),
-  bottom10Avg: z.number(),
-  excellentRate: z.number(),
-  passRate: z.number(),
-  activeRate: z.number(),
-  acRate: z.number(),
-  compositeScore: z.number(),
-  recentTotalAc: z.number().int().optional(),
-  recentTotalSubmission: z.number().int().optional(),
-  recentAvgAc: z.number().optional(),
-  recentMedianAc: z.number().optional(),
-  recentTop10Avg: z.number().optional(),
-  recentActiveCount: z.number().int().optional(),
-})
-
-export const classComparisonRequestSchema = z.object({
-  classNames: z.array(z.string()).min(1),
-  startTime: z.string().optional(),
-  endTime: z.string().optional(),
-})
-
-export const classComparisonResponseSchema = z.object({
-  comparisons: z.array(classComparisonSchema),
-  hasTimeRange: z.boolean(),
-})
-
 /**
  * 「班里在做」：同班同一天有好几个人做的题，基本就是老师在课上点名的那几道。
  * `day` 是东八区日历日；最近 7 天都没有这样的题时为 null，`problems` 为空。
@@ -200,9 +162,6 @@ export const classLessonSchema = z.object({
   problems: z.array(z.object({ problemDisplayId: z.string(), title: z.string() })),
 })
 
-export type ClassComparison = z.infer<typeof classComparisonSchema>
-export type ClassComparisonResponse = z.infer<typeof classComparisonResponseSchema>
-
 export type ClassActivity = z.infer<typeof classActivitySchema>
 export type LastVisit = z.infer<typeof lastVisitSchema>
 export type ClassLessonRequest = z.infer<typeof classLessonRequestSchema>
@@ -212,5 +171,3 @@ export type ClassBoardProblem = z.infer<typeof classBoardProblemSchema>
 export type ClassBoardStudent = z.infer<typeof classBoardStudentSchema>
 export type ClassBoardCell = z.infer<typeof classBoardCellSchema>
 export type ClassActivityProblem = z.infer<typeof classActivityProblemSchema>
-
-export type ClassComparisonRequest = z.infer<typeof classComparisonRequestSchema>

packages/contract/src/ranking.ts

@@ -146,3 +146,86 @@ export const classDetailSchema = z.object({
 })
 
 export type ClassDetail = z.infer<typeof classDetailSchema>
+
+/**
+ * 班级 PK（设计稿「班级 PK 重设计」定稿）。用户定的：**两个班按「同一批题」对决，三个班以上
+ * 按题对照，学生也能看**。
+ *
+ * 各班进度不同、布置的题不一样，比人均等于比谁开课早，所以主角是「同一批题」：
+ * 一个班过半的人交过这道题就算这个班**布置过**；至少两个班布置过的题才拿来比，
+ * 比的是**做对的人占全班几成**（整数百分比），高的那个班赢这道，显示一样就算平 ——
+ * 不然 37/39 和 38/40 都显示 95%，皇冠却只给一边。口径和排名页一样：比赛里的提交不算，
+ * 不计入排名的人分子分母都不算。
+ */
+export const classPkPeriodSchema = z.enum(["week", "term"])
+
+export const classPkCellSchema = z.object({
+  /** 这段时间交过这道题的人 */
+  tried: z.number().int().nonnegative(),
+  /** 这段时间做对了的人 */
+  solved: z.number().int().nonnegative(),
+  /** 第一次交就对的人 */
+  firstTry: z.number().int().nonnegative(),
+  submissions: z.number().int().nonnegative(),
+  /** 做对的人占全班几成（整数百分比），比输赢就比它 */
+  percent: z.number().int().nonnegative(),
+  /** 一次就对：交过的人里第一次交就对的占几成 */
+  firstPercent: z.number().int().nonnegative(),
+  /** 这道题做得最好的班（一样多就都算） */
+  best: z.boolean(),
+})
+
+export const classPkProblemSchema = z.object({
+  problemId: z.number().int(),
+  displayId: z.string(),
+  title: z.string(),
+  /** 和 `classes` 一一对应；null = 这个班没布置 */
+  cells: z.array(classPkCellSchema.nullable()),
+})
+
+export const classPkClassSchema = z.object({
+  className: z.string(),
+  members: z.number().int().nonnegative(),
+  /** 这段时间人均做对（这道题第一次做对落在这段时间里） */
+  perCapita: z.number(),
+  /** 中间那位同学做对几道 */
+  median: z.number(),
+  solvedMembers: z.number().int().nonnegative(),
+  /** 这段时间交过的题里第一次交就对的比例（整数百分比）；一道没交过为 null */
+  firstPercent: z.number().int().nonnegative().nullable(),
+  /** 同一批题里做得最好（含并列）的有几道 */
+  lead: z.number().int().nonnegative(),
+  /** 班级对抗里第几；这学期还没做对过题的班没有名次 */
+  battleRank: z.number().int().positive().nullable(),
+  /** 每个同学这段时间做对几道 */
+  distribution: z.array(z.number().int().nonnegative()),
+  /** 这学期每周人均新做对，和 `weeks` 一一对应（不随「这周 / 这学期」变） */
+  weekly: z.array(z.number()),
+})
+
+export const classPkSchema = z.object({
+  period: classPkPeriodSchema,
+  start: z.string(),
+  /** 这学期每周的周一零点（东八区），赛跑和每周人均的横轴 */
+  weeks: z.array(z.string()),
+  classes: z.array(classPkClassSchema),
+  /** 看的人自己的班（学生）；老师和没班级的为 null */
+  mine: z.string().nullable(),
+  /** 至少两个班布置过的题，按题号 */
+  problems: z.array(classPkProblemSchema),
+  /** 只有一个班布置过的题：不比，只列出来 */
+  solo: z.array(
+    z.object({
+      problemId: z.number().int(),
+      displayId: z.string(),
+      title: z.string(),
+      className: z.string(),
+    }),
+  ),
+})
+
+export type ClassPkPeriod = z.infer<typeof classPkPeriodSchema>
+export type ClassPkCell = z.infer<typeof classPkCellSchema>
+export type ClassPkProblem = z.infer<typeof classPkProblemSchema>
+export type ClassPkClass = z.infer<typeof classPkClassSchema>
+export type ClassPk = z.infer<typeof classPkSchema>