diff --git a/packages/hydrojudge/src/flow.ts b/packages/hydrojudge/src/flow.ts
new file mode 100644
index 000000000..0fa5a1b0b
--- /dev/null
+++ b/packages/hydrojudge/src/flow.ts
@@ -0,0 +1,94 @@
+import Queue from 'p-queue';
+import { STATUS } from '@hydrooj/utils/lib/status';
+import { getConfig } from './config';
+import { CompileError, FormatError } from './error';
+import { Context, ContextSubTask } from './judge/interface';
+import { NormalizedCase, NormalizedSubtask } from './utils';
+
+interface Task {
+    compile: () => Promise<void>;
+    judgeCase: (c: NormalizedCase, sid: string) => (
+        (ctx: Context, ctxSubtask: ContextSubTask, runner?: Function) => Promise<any>
+    )
+}
+
+function judgeSubtask(subtask: NormalizedSubtask, sid: string, judgeCase: Task['judgeCase']) {
+    return async (ctx: Context) => {
+        subtask.type = subtask.type || 'min';
+        const ctxSubtask = {
+            subtask,
+            status: 0,
+            score: subtask.type === 'min'
+                ? subtask.score
+                : 0,
+        };
+        const cases = [];
+        for (const cid in subtask.cases) {
+            const runner = judgeCase(subtask.cases[cid], subtask.id.toString() ?? sid);
+            cases.push(ctx.queue.add(async () => {
+                if (ctx.errored
+                    || (ctxSubtask.subtask.type === 'min' && ctxSubtask.score === 0)
+                    || (ctxSubtask.subtask.type === 'max' && ctxSubtask.score === ctxSubtask.subtask.score)
+                    || ((ctxSubtask.subtask.if || []).filter((i) => ctx.failed[i]).length)
+                ) {
+                    ctx.next({
+                        case: {
+                            id: subtask.cases[cid].id,
+                            status: STATUS.STATUS_CANCELED,
+                            subtaskId: subtask.id,
+                            score: 0,
+                            time: 0,
+                            memory: 0,
+                            message: '',
+                        },
+                        addProgress: 100 / ctx.config.count,
+                    });
+                } else await runner(ctx, ctxSubtask, runner);
+            }));
+        }
+        await Promise.all(cases).catch((e) => {
+            ctx.errored = true;
+            throw e;
+        });
+        ctx.total_status = Math.max(ctx.total_status, ctxSubtask.status);
+        return ctxSubtask.score;
+    };
+}
+
+export const runFlow = async (ctx: Context, task: Task) => {
+    if (!ctx.config.subtasks.length) throw new FormatError('Problem data not found.');
+    ctx.next({ status: STATUS.STATUS_COMPILING });
+    if (ctx.config.template && 'content' in ctx.code) {
+        if (ctx.config.template[ctx.lang]) {
+            const tpl = ctx.config.template[ctx.lang];
+            ctx.code.content = tpl[0] + ctx.code.content + tpl[1];
+        } else throw new CompileError('Language not supported by provided templates');
+    }
+    await task.compile();
+    ctx.next({ status: STATUS.STATUS_JUDGING, progress: 0 });
+    const tasks = [];
+    ctx.total_status = 0;
+    ctx.total_score = 0;
+    ctx.total_memory_usage_kb = 0;
+    ctx.total_time_usage_ms = 0;
+    ctx.rerun = getConfig('rerun') || 0;
+    ctx.queue = new Queue({ concurrency: getConfig('singleTaskParallelism') });
+    ctx.failed = {};
+    for (const sid in ctx.config.subtasks) tasks.push(judgeSubtask(ctx.config.subtasks[sid], sid, task.judgeCase)(ctx));
+    const scores = await Promise.all(tasks);
+    for (const sid in ctx.config.subtasks) {
+        let effective = true;
+        for (const required of ctx.config.subtasks[sid].if || []) {
+            if (ctx.failed[required.toString()]) effective = false;
+        }
+        if (effective) ctx.total_score += scores[sid];
+    }
+    ctx.stat.done = new Date();
+    if (process.env.DEV) ctx.next({ message: JSON.stringify(ctx.stat) });
+    ctx.end({
+        status: ctx.total_status,
+        score: ctx.total_score,
+        time: Math.floor(ctx.total_time_usage_ms * 1000000) / 1000000,
+        memory: ctx.total_memory_usage_kb,
+    });
+};
diff --git a/packages/hydrojudge/src/judge/default.ts b/packages/hydrojudge/src/judge/default.ts
index c6e5a9198..a8ad2c57a 100644
--- a/packages/hydrojudge/src/judge/default.ts
+++ b/packages/hydrojudge/src/judge/default.ts
@@ -1,13 +1,11 @@
-import Queue from 'p-queue';
 import { STATUS } from '@hydrooj/utils/lib/status';
 import { check, compileChecker } from '../check';
 import compile from '../compile';
-import { getConfig } from '../config';
-import { CompileError, FormatError } from '../error';
+import { runFlow } from '../flow';
 import { Logger } from '../log';
 import { CmdFile, del, run } from '../sandbox';
 import signals from '../signals';
-import { NormalizedCase, NormalizedSubtask, parseFilename } from '../utils';
+import { NormalizedCase, parseFilename } from '../utils';
 import { Context, ContextSubTask } from './interface';
 
 const Score = {
@@ -20,25 +18,6 @@ const logger = new Logger('judge/default');
 
 function judgeCase(c: NormalizedCase, sid: string) {
     return async (ctx: Context, ctxSubtask: ContextSubTask, runner?: Function) => {
-        if (ctx.errored
-            || (ctxSubtask.subtask.type === 'min' && ctxSubtask.score === 0)
-            || (ctxSubtask.subtask.type === 'max' && ctxSubtask.score === ctxSubtask.subtask.score)
-            || ((ctxSubtask.subtask.if || []).filter((i) => ctx.failed[i]).length)
-        ) {
-            ctx.next({
-                case: {
-                    id: c.id,
-                    status: STATUS.STATUS_CANCELED,
-                    subtaskId: ctxSubtask.subtask.id,
-                    score: 0,
-                    time: 0,
-                    memory: 0,
-                    message: '',
-                },
-                addProgress: 100 / ctx.config.count,
-            });
-            return;
-        }
         const { filename } = ctx.config;
         const copyIn = { ...ctx.execute.copyIn };
         if (filename) copyIn[`${filename}.in`] = c.input ? { src: c.input } : { content: '' };
@@ -140,84 +119,29 @@ function judgeCase(c: NormalizedCase, sid: string) {
     };
 }
 
-function judgeSubtask(subtask: NormalizedSubtask, sid: string) {
-    return async (ctx: Context) => {
-        subtask.type = subtask.type || 'min';
-        const ctxSubtask = {
-            subtask,
-            status: 0,
-            score: subtask.type === 'min'
-                ? subtask.score
-                : 0,
-        };
-        const cases = [];
-        for (const cid in subtask.cases) {
-            const runner = judgeCase(subtask.cases[cid], subtask.id.toString() ?? sid);
-            cases.push(ctx.queue.add(() => runner(ctx, ctxSubtask, runner)));
-        }
-        await Promise.all(cases).catch((e) => {
-            ctx.errored = true;
-            throw e;
-        });
-        ctx.total_status = Math.max(ctx.total_status, ctxSubtask.status);
-        return ctxSubtask.score;
-    };
-}
-
-export const judge = async (ctx: Context) => {
-    if (!ctx.config.subtasks.length) throw new FormatError('Problem data not found.');
-    ctx.next({ status: STATUS.STATUS_COMPILING });
-    if (ctx.config.template && 'content' in ctx.code) {
-        if (ctx.config.template[ctx.lang]) {
-            const tpl = ctx.config.template[ctx.lang];
-            ctx.code.content = tpl[0] + ctx.code.content + tpl[1];
-        } else throw new CompileError('Language not supported by provided templates');
-    }
-    [ctx.execute, ctx.checker] = await Promise.all([
-        compile(
-            ctx.session.getLang(ctx.lang), ctx.code,
-            Object.fromEntries(
-                (ctx.config.user_extra_files || []).map((i) => [i.split('/').pop(), { src: i }]),
-            ),
-            ctx.next,
-        ),
-        compileChecker(
-            ctx.session.getLang,
-            ctx.config.checker_type,
-            ctx.config.checker,
-            {
-                user_code: ctx.code,
-                ...Object.fromEntries(
-                    (ctx.config.judge_extra_files || []).map((i) => [parseFilename(i), { src: i }]),
+export const judge = async (ctx: Context) => await runFlow(ctx, {
+    compile: async () => {
+        [ctx.execute, ctx.checker] = await Promise.all([
+            compile(
+                ctx.session.getLang(ctx.lang), ctx.code,
+                Object.fromEntries(
+                    (ctx.config.user_extra_files || []).map((i) => [i.split('/').pop(), { src: i }]),
                 ),
-            },
-        ),
-    ]);
-    ctx.clean.push(ctx.execute.clean, ctx.checker.clean);
-    ctx.next({ status: STATUS.STATUS_JUDGING, progress: 0 });
-    const tasks = [];
-    ctx.total_status = 0;
-    ctx.total_score = 0;
-    ctx.total_memory_usage_kb = 0;
-    ctx.total_time_usage_ms = 0;
-    ctx.rerun = getConfig('rerun') || 0;
-    ctx.queue = new Queue({ concurrency: getConfig('singleTaskParallelism') });
-    ctx.failed = {};
-    for (const sid in ctx.config.subtasks) tasks.push(judgeSubtask(ctx.config.subtasks[sid], sid)(ctx));
-    const scores = await Promise.all(tasks);
-    for (const sid in ctx.config.subtasks) {
-        let effective = true;
-        for (const required of ctx.config.subtasks[sid].if || []) {
-            if (ctx.failed[required.toString()]) effective = false;
-        }
-        if (effective) ctx.total_score += scores[sid];
-    }
-    ctx.stat.done = new Date();
-    if (process.env.DEV) ctx.next({ message: JSON.stringify(ctx.stat) });
-    ctx.end({
-        status: ctx.total_status,
-        score: ctx.total_score,
-        time: Math.floor(ctx.total_time_usage_ms * 1000000) / 1000000,
-        memory: ctx.total_memory_usage_kb,
-    });
-};
+                ctx.next,
+            ),
+            compileChecker(
+                ctx.session.getLang,
+                ctx.config.checker_type,
+                ctx.config.checker,
+                {
+                    user_code: ctx.code,
+                    ...Object.fromEntries(
+                        (ctx.config.judge_extra_files || []).map((i) => [parseFilename(i), { src: i }]),
+                    ),
+                },
+            ),
+        ]);
+        ctx.clean.push(ctx.execute.clean, ctx.checker.clean);
+    },
+    judgeCase,
+});
diff --git a/packages/hydrojudge/src/judge/interactive.ts b/packages/hydrojudge/src/judge/interactive.ts
index f2c71fc06..8289ac5e2 100644
--- a/packages/hydrojudge/src/judge/interactive.ts
+++ b/packages/hydrojudge/src/judge/interactive.ts
@@ -1,12 +1,11 @@
-import Queue from 'p-queue';
 import { STATUS } from '@hydrooj/utils/lib/status';
 import compile from '../compile';
-import { getConfig } from '../config';
+import { runFlow } from '../flow';
 import { runPiped } from '../sandbox';
 import signals from '../signals';
 import { parse } from '../testlib';
 import {
-    findFileSync, NormalizedCase, NormalizedSubtask, parseFilename,
+    findFileSync, NormalizedCase, parseFilename,
 } from '../utils';
 import { Context, ContextSubTask } from './interface';
 
@@ -76,66 +75,32 @@ function judgeCase(c: NormalizedCase) {
     };
 }
 
-function judgeSubtask(subtask: NormalizedSubtask) {
-    return async (ctx: Context) => {
-        subtask.type = subtask.type || 'min';
-        const ctxSubtask = {
-            subtask,
-            status: 0,
-            score: subtask.type === 'min'
-                ? subtask.score
-                : 0,
-        };
-        const cases = [];
-        for (const cid in subtask.cases) {
-            cases.push(ctx.queue.add(() => judgeCase(subtask.cases[cid])(ctx, ctxSubtask)));
-        }
-        await Promise.all(cases);
-        ctx.total_status = Math.max(ctx.total_status, ctxSubtask.status);
-        ctx.total_score += ctxSubtask.score;
-    };
-}
-
-export const judge = async (ctx: Context) => {
-    ctx.next({ status: STATUS.STATUS_COMPILING });
-    [ctx.executeUser, ctx.executeInteractor] = await Promise.all([
-        (() => {
-            const copyIn = {};
-            for (const file of ctx.config.user_extra_files) {
-                copyIn[parseFilename(file)] = { src: file };
-            }
-            return compile(ctx.session.getLang(ctx.lang), ctx.code, copyIn, ctx.next);
-        })(),
-        (() => {
-            const copyIn = {
-                'testlib.h': { src: testlibSrc },
-                user_code: ctx.code,
-            };
-            for (const file of ctx.config.judge_extra_files) {
-                copyIn[parseFilename(file)] = { src: file };
-            }
-            return compile(
-                ctx.session.getLang(parseFilename(ctx.config.interactor).split('.')[1].replace('@', '.')),
-                { src: ctx.config.interactor },
-                copyIn,
-            );
-        })(),
-    ]);
-    ctx.clean.push(ctx.executeUser.clean, ctx.executeInteractor.clean);
-    ctx.next({ status: STATUS.STATUS_JUDGING, progress: 0 });
-    const tasks = [];
-    ctx.total_status = ctx.total_score = ctx.total_memory_usage_kb = ctx.total_time_usage_ms = 0;
-    ctx.queue = new Queue({ concurrency: getConfig('parallelism') });
-    for (const sid in ctx.config.subtasks) {
-        tasks.push(judgeSubtask(ctx.config.subtasks[sid])(ctx));
-    }
-    await Promise.all(tasks);
-    ctx.stat.done = new Date();
-    if (process.env.DEV) ctx.next({ message: JSON.stringify(ctx.stat) });
-    ctx.end({
-        status: ctx.total_status,
-        score: ctx.total_score,
-        time: ctx.total_time_usage_ms,
-        memory: ctx.total_memory_usage_kb,
-    });
-};
+export const judge = async (ctx: Context) => await runFlow(ctx, {
+    compile: async () => {
+        [ctx.executeUser, ctx.executeInteractor] = await Promise.all([
+            (() => {
+                const copyIn = {};
+                for (const file of ctx.config.user_extra_files) {
+                    copyIn[parseFilename(file)] = { src: file };
+                }
+                return compile(ctx.session.getLang(ctx.lang), ctx.code, copyIn, ctx.next);
+            })(),
+            (() => {
+                const copyIn = {
+                    'testlib.h': { src: testlibSrc },
+                    user_code: ctx.code,
+                };
+                for (const file of ctx.config.judge_extra_files) {
+                    copyIn[parseFilename(file)] = { src: file };
+                }
+                return compile(
+                    ctx.session.getLang(parseFilename(ctx.config.interactor).split('.')[1].replace('@', '.')),
+                    { src: ctx.config.interactor },
+                    copyIn,
+                );
+            })(),
+        ]);
+        ctx.clean.push(ctx.executeUser.clean, ctx.executeInteractor.clean);
+    },
+    judgeCase,
+});
diff --git a/packages/hydrojudge/src/judge/submit_answer.ts b/packages/hydrojudge/src/judge/submit_answer.ts
index 6e273321e..006ca208a 100644
--- a/packages/hydrojudge/src/judge/submit_answer.ts
+++ b/packages/hydrojudge/src/judge/submit_answer.ts
@@ -1,11 +1,9 @@
 import { readFile } from 'fs-extra';
-import Queue from 'p-queue';
 import { STATUS } from '@hydrooj/utils/lib/status';
 import { check, compileChecker } from '../check';
-import { getConfig } from '../config';
-import { FormatError } from '../error';
+import { runFlow } from '../flow';
 import { del, run } from '../sandbox';
-import { NormalizedCase, NormalizedSubtask, parseFilename } from '../utils';
+import { NormalizedCase, parseFilename } from '../utils';
 import { Context, ContextSubTask } from './interface';
 
 const Score = {
@@ -16,23 +14,6 @@ const Score = {
 
 function judgeCase(c: NormalizedCase, sid: string) {
     return async (ctx: Context, ctxSubtask: ContextSubTask) => {
-        if (ctx.errored || (ctx.failed[sid] && ctxSubtask.subtask.type === 'min')
-            || (ctxSubtask.subtask.type === 'max' && ctxSubtask.score === ctxSubtask.subtask.score)
-            || ((ctxSubtask.subtask.if || []).filter((i) => ctx.failed[i]).length)
-        ) {
-            ctx.next({
-                case: {
-                    id: c.id,
-                    status: STATUS.STATUS_CANCELED,
-                    score: 0,
-                    time: 0,
-                    memory: 0,
-                    message: '',
-                },
-                addProgress: 100 / ctx.config.count,
-            });
-            return;
-        }
         const chars = /[a-zA-Z0-9_.-]/;
         const name = (ctx.config.filename && /^[a-zA-Z0-9-_#.]+$/.test(ctx.config.filename))
             ? ctx.config.filename.replace('#', c.id.toString())
@@ -96,67 +77,23 @@ function judgeCase(c: NormalizedCase, sid: string) {
     };
 }
 
-function judgeSubtask(subtask: NormalizedSubtask, sid: string) {
-    return async (ctx: Context) => {
-        subtask.type = subtask.type || 'min';
-        const ctxSubtask = {
-            subtask,
-            status: 0,
-            score: subtask.type === 'min'
-                ? subtask.score
-                : 0,
-        };
-        const cases = [];
-        for (const cid in subtask.cases) {
-            const runner = judgeCase(subtask.cases[cid], sid);
-            cases.push(ctx.queue.add(() => runner(ctx, ctxSubtask)));
-        }
-        await Promise.all(cases).catch((e) => {
-            ctx.errored = true;
-            throw e;
-        });
-        ctx.total_status = Math.max(ctx.total_status, ctxSubtask.status);
-        return ctxSubtask.score;
-    };
-}
-
 export const judge = async (ctx: Context) => {
-    if (!ctx.config.subtasks.length) throw new FormatError('Problem data not found.');
-    ctx.next({ status: STATUS.STATUS_COMPILING });
-    ctx.checker = await (() => {
-        const copyIn = { user_code: ctx.code };
-        for (const file of ctx.config.judge_extra_files) {
-            copyIn[parseFilename(file)] = { src: file };
-        }
-        return compileChecker(
-            ctx.session.getLang,
-            ctx.config.checker_type,
-            ctx.config.checker,
-            copyIn,
-        );
-    })();
-    ctx.clean.push(ctx.checker.clean);
-    ctx.next({ status: STATUS.STATUS_JUDGING, progress: 0 });
-    const tasks = [];
-    ctx.total_status = 0;
-    ctx.total_score = 0;
-    ctx.queue = new Queue({ concurrency: getConfig('parallelism') });
-    ctx.failed = {};
-    for (const sid in ctx.config.subtasks) tasks.push(judgeSubtask(ctx.config.subtasks[sid], sid)(ctx));
-    const scores = await Promise.all(tasks);
-    for (const sid in ctx.config.subtasks) {
-        let effective = true;
-        for (const required of ctx.config.subtasks[sid].if || []) {
-            if (ctx.failed[required.toString()]) effective = false;
-        }
-        if (effective) ctx.total_score += scores[sid];
-    }
-    ctx.stat.done = new Date();
-    if (process.env.DEV) ctx.next({ message: JSON.stringify(ctx.stat) });
-    ctx.end({
-        status: ctx.total_status,
-        score: ctx.total_score,
-        time: 0,
-        memory: 0,
+    await runFlow(ctx, {
+        compile: async () => {
+            ctx.checker = await (() => {
+                const copyIn = { user_code: ctx.code };
+                for (const file of ctx.config.judge_extra_files) {
+                    copyIn[parseFilename(file)] = { src: file };
+                }
+                return compileChecker(
+                    ctx.session.getLang,
+                    ctx.config.checker_type,
+                    ctx.config.checker,
+                    copyIn,
+                );
+            })();
+            ctx.clean.push(ctx.checker.clean);
+        },
+        judgeCase,
     });
 };