diff --git a/server/src/entities/submission.entity.ts b/server/src/entities/submission.entity.ts
index ca49ce5..f0f4486 100644
--- a/server/src/entities/submission.entity.ts
+++ b/server/src/entities/submission.entity.ts
@@ -1,4 +1,3 @@
-import { Status } from '../const/boj-results';
 import {
   BaseEntity,
   Column,
@@ -6,6 +5,7 @@ import {
   ManyToOne,
   PrimaryGeneratedColumn,
 } from 'typeorm';
+import { Status } from '../const/boj-results';
 import Problem from './problem.entity';
 import Room from './room.entity';
 import User from './user.entity';
@@ -37,4 +37,7 @@ export default class Submission extends BaseEntity {
 
   @ManyToOne(() => Problem, (problem) => problem.submissions, { cascade: true })
   problem?: Problem;
+
+  @Column()
+  alreadyAccepted!: boolean;
 }
diff --git a/server/src/room/room-code/room-code.pipe.spec.ts b/server/src/room/room-code/room-code.pipe.spec.ts
new file mode 100644
index 0000000..99b4ac5
--- /dev/null
+++ b/server/src/room/room-code/room-code.pipe.spec.ts
@@ -0,0 +1,7 @@
+import { RoomCodePipe } from './room-code.pipe';
+
+describe('RoomCodePipe', () => {
+  it('should be defined', () => {
+    expect(new RoomCodePipe()).toBeDefined();
+  });
+});
diff --git a/server/src/room/room-code/room-code.pipe.ts b/server/src/room/room-code/room-code.pipe.ts
new file mode 100644
index 0000000..781d5a9
--- /dev/null
+++ b/server/src/room/room-code/room-code.pipe.ts
@@ -0,0 +1,19 @@
+import {
+  ArgumentMetadata,
+  BadRequestException,
+  Injectable,
+  PipeTransform,
+} from '@nestjs/common';
+
+@Injectable()
+export class RoomCodePipe implements PipeTransform {
+  transform(value: any, _metadata: ArgumentMetadata) {
+    const hexRegExp = /^[0-9a-fA-F]{6}$/;
+
+    if (!hexRegExp.test(value)) {
+      throw new BadRequestException('Invalid room code');
+    }
+
+    return value;
+  }
+}
diff --git a/server/src/room/room.controller.ts b/server/src/room/room.controller.ts
index 62fc72b..4e7d742 100644
--- a/server/src/room/room.controller.ts
+++ b/server/src/room/room.controller.ts
@@ -15,6 +15,7 @@ import { Request } from 'express';
 import { SessionAuthGuard } from '../auth/auth.guard';
 import User from '../entities/user.entity';
 import { RoomUserService } from '../room-user/room-user.service';
+import { RoomCodePipe } from './room-code/room-code.pipe';
 import { RoomService } from './room.service';
 
 @Controller('room')
@@ -69,4 +70,10 @@ export class RoomController {
   async getRoomUsers(@Param('code') code: string) {
     return await this.roomUserService.findUsersByRoomCode(code);
   }
+
+  @Get('/:code/rankings')
+  @HttpCode(HttpStatus.OK)
+  async getRoomRankings(@Param('code', RoomCodePipe) code: string) {
+    return await this.roomService.getRoomRankings(code);
+  }
 }
diff --git a/server/src/room/room.service.ts b/server/src/room/room.service.ts
index 9c9003c..82f2c8a 100644
--- a/server/src/room/room.service.ts
+++ b/server/src/room/room.service.ts
@@ -1,17 +1,19 @@
 import {
   BadRequestException,
+  forwardRef,
   Inject,
   Injectable,
   InternalServerErrorException,
   Logger,
-  forwardRef,
 } from '@nestjs/common';
 import { InjectRepository } from '@nestjs/typeorm';
 import * as crypto from 'crypto';
 import { isNil } from 'src/common/utils';
 import { SubmissionService } from 'src/submission/submission.service';
 import { Repository } from 'typeorm';
+import { Status } from '../const/boj-results';
 import Room from '../entities/room.entity';
+import Submission from '../entities/submission.entity';
 import User from '../entities/user.entity';
 import RoomUser from '../room-user/room-user.entity';
 import { RoomUserService } from '../room-user/room-user.service';
@@ -130,4 +132,36 @@ export class RoomService {
     }
     return room;
   }
+
+  /**
+   * returns an array of user id, username, and the number of accepted problems of the user, sorted by the number of accepted problems
+   * @param code
+   */
+  async getRoomRankings(code: string) {
+    Submission;
+    User;
+    const qb = this.roomRepository
+      .createQueryBuilder('room')
+      .where('room.code = :code', { code })
+      .innerJoin('room.joinedUsers', 'roomUser')
+      .innerJoin('roomUser.user', 'user')
+      .innerJoin(
+        'room.submissions',
+        'submission',
+        'submission.status = :status AND submission.user_id = user.id AND submission.alreadyAccepted = false',
+        {
+          status: Status.ACCEPTED,
+        },
+      )
+      .select('user.id', 'userId')
+      .addSelect('user.username', 'username')
+      .addSelect('COUNT(submission.id)', 'acceptedCount')
+      .addSelect('MAX(submission.submittedAt)', 'lastAcceptedAt')
+      .groupBy('user.id')
+      .orderBy('acceptedCount', 'DESC')
+      .addOrderBy('lastAcceptedAt', 'ASC');
+
+    const data = await qb.getRawMany();
+    return { data };
+  }
 }
diff --git a/server/src/submission/submission.service.ts b/server/src/submission/submission.service.ts
index b181801..8129169 100644
--- a/server/src/submission/submission.service.ts
+++ b/server/src/submission/submission.service.ts
@@ -105,6 +105,15 @@ export class SubmissionService {
       status,
     );
 
+    const alreadyAccepted = await this.submissionRepository.exist({
+      where: {
+        user: { id: user.id },
+        problem: { id: problem.id },
+        room: { id: room.id },
+        status: Status.ACCEPTED,
+      },
+    });
+
     return await this.submissionRepository
       .create({
         status,
@@ -112,6 +121,7 @@ export class SubmissionService {
         room,
         problem,
         submittedAt,
+        alreadyAccepted,
       })
       .save();
   }