Train like thetop 1%.
A focused workspace for competitive programming: a Monaco-powered IDE, real Codeforces & CSES judging, a Gemini AI mentor that guides instead of spoiling, a structured roadmap, and 20+ interactive algorithm visualizers.
#include <bits/stdc++.h>
using namespace std;
int main() {
int n, q; cin >> n >> q;
vector<long long> pre(n + 1);
for (int i = 1; i <= n; ++i) {
int x; cin >> x;
pre[i] = pre[i - 1] + x;
}
}Your O(n) idea is right. Before you code the range queries, what could you precompute so each query becomes O(1)?
Built for real training, not interview prep
Every part of the platform exists to shorten the loop between reading a problem and understanding why your solution works.
A real competitive IDE
Monaco editor with syntax highlighting and five languages — C++, Python, Java, Rust and Go — plus your own code templates. Run against the samples in a single keystroke.
An AI mentor that won't spoil
A Gemini-powered mentor built on Pólya's method. It diagnoses your thinking and gives graduated hints — the next step, never the whole solution.
Real judging, not mocks
Submit straight to Codeforces and CSES through the platform, or get an instant verdict checked against the sample tests. Status and verdicts stream back live.
A structured roadmap
Follow a staged syllabus from fundamentals to advanced DP and graphs, with readable articles and curated problems linked to every topic.
20+ interactive visualizers
Watch Dijkstra, segment trees, DSU, sorting and more run step by step, so the algorithm becomes intuition instead of memorized code.
Progress you can see
A GitHub-style activity heatmap, verdict analytics, streaks and full submission history keep your weak spots and momentum in plain view.
See the algorithm, not just the code
Over twenty hand-built visualizers animate the data structures and techniques that show up again and again in contests.
From problem to intuition in four steps
Pick a path
Start from the roadmap or jump into a problem matched to your current skill level.
Solve in the IDE
Write, run against samples, and submit — to Codeforces, CSES, or the instant judge.
Get unstuck, not spoiled
Ask the AI mentor for the next hint, or replay the relevant visualizer until it clicks.
Track your growth
Watch your heatmap fill in and your verdict analytics sharpen over time.
Hints that build intuition
The mentor follows a hint ladder: a diagnostic question first, a stronger nudge only if you're still stuck, and a full walkthrough only when you ask for it.
- Pinpoints where your reasoning breaks down
- Reviews your code — idea, correctness, complexity, edge cases
- Reveals the full solution only when you explicitly ask
Also included
Spoiler protection
Hide tags and difficulty to recreate real contest conditions.
Adaptive recommendations
A skill-axis matching engine suggests problems at the edge of your ability.
Graph editor & whiteboard
Sketch graphs and reason visually without leaving the browser.
Bilingual interface
Use the entire platform in English or Russian.