Video Solutions
We publish free, full walkthroughs of past contest problems and AP questions — the same way we teach in class: read the problem, find the idea, write the code, test it. Watch on YouTube or on 小红书 (RedNote) if you’re in China. 国内的同学和家长可以直接在小红书观看，内容同步更新。
New videos land weekly during contest season. Subscribe so you don’t miss the next CCC / USACO cycle — and if you want a specific problem covered, ask us or request it in the forum.
CCC Junior（加拿大计算机竞赛 · 初级）
Complete walkthroughs of past CCC Junior problems (J1–J5), in Python and C++.
| Series 系列 | YouTube | 小红书 RedNote |
|---|---|---|
| CCC Junior — full playlist 全集 | ▶ Watch the playlist | 📕 小红书合集 |
AP Computer Science A（Java）
FRQ walkthroughs and MCQ traps, aligned to the current College Board CED.
| Series 系列 | YouTube | 小红书 RedNote |
|---|---|---|
| AP CSA — FRQ walkthroughs | ▶ Playlist | 📕 小红书合集 |
USACO Bronze（美国信息学奥赛 · 铜级）
Simulation, sorting and complete-search patterns — everything Bronze tests.
| Series 系列 | YouTube | 小红书 RedNote |
|---|---|---|
| USACO Bronze — past contests | ▶ Playlist | 📕 小红书合集 |
NOI Junior / CSP-J（中国信息学奥赛 · 入门级）
CSP-J 真题精讲（C++），讲解思路与代码实现，适合准备 CSP-J 第一轮与第二轮的同学。
| Series 系列 | YouTube | 小红书 RedNote |
|---|---|---|
| CSP-J 真题精讲 | ▶ Playlist | 📕 小红书合集 |
Want the methods behind the solutions, not just answers? That’s what the Coding Competitions course is for — weekly problem sets on our own judge, with personal feedback. Enroll here.