LogN

Reduce the complexity. LogN is competitive programming practice built for your phone. Each session takes about three minutes and follows the grammar of a programming contest: problems by letter, a balloon per color, three lives and a clock running. NO BLANK EDITOR Typing whole programs on a phone keyboard teaches nobody. Each question isolates one decision — the right line, the bug, the complexity — and fits in a bus queue. FOUR FORMATS • Complete the line: the algorithm is done except for one line. Pick it from nearly identical candidates. • Find the bug: six lines, one wrong. Tap the one that breaks on the edge case. • Match the complexity: drag each snippet to the right notation, O(1), O(log n), O(n), O(n²). • Dry run: run it in your head and say what comes out. No compiling, no print. THE JUDGE EXPLAINS Verdicts come like a real judge's: AC, WA, TLE, RE. Fell for a classic trap — off-by-one, overflow in mid, visited marked too late — and the app explains why before the next question. THE CURRICULUM IS A GRAPH Each technique is a balloon; each prerequisite, a string. A technique only opens after the ones it builds on, and the map shows why. TRACKS • Algorithms and data structures: the main track, free. • DevOps and AI engineering: paid tracks, with a free sample to play first. One-time purchase, tied to your account, updates at no cost, and the track opens offline. WORKS OFFLINE Answered on the subway? Progress stays on the device and syncs when the connection comes back. OPEN SOURCE Core, clients and backend are on GitHub to read, fork and send PRs. Only the questions stay in the drawer — publishing the answer key would spoil the contest. Sign in with email, Google or GitHub. You can delete your account from inside the app whenever you want.