submission exists api

submission/views/oj.py

@@ -200,3 +200,12 @@ class ContestSubmissionListAPI(APIView):
         data = self.paginate_data(request, submissions)
         data["results"] = SubmissionListSerializer(data["results"], many=True, user=request.user).data
         return self.success(data)
+
+
+class SubmissionExistsAPI(APIView):
+    def get(self, request):
+        if not request.GET.get("problem_id"):
+            return self.error("Parameter error, problem_id is required")
+        return self.success(request.user.is_authenticated and
+                            Submission.objects.filter(problem_id=request.GET["problem_id"],
+                                                      user_id=request.user.id).exists())