Lichen: Big-O Algorithms

Big-O at a glance. Catalog, chart, and quiz for every classic algorithm — fully offline.

Lichen is a focused, offline reference for classical algorithms and their Big-O complexity. Built for students, interview candidates, and working engineers who want fast answers without noise.

A clean catalog, a side-by-side growth chart, and a quick quiz mode — all on a single dark stage. No clutter, no popups, no upsells.

KEY FEATURES • Catalog of 30+ algorithms across Sort, Search, Graph, Tree, String, Dynamic Programming, Divide & Conquer, Greedy, Hashing, and Heap • Best, average, worst, and space complexities for every algorithm • Live growth-rate chart comparing O(1), O(log n), O(n), O(n log n), O(n²), O(2ⁿ), and O(n!) • Pseudocode snippets and real-world use cases on every detail page • Filter by category and by complexity class with single-tap chips • Bookmark algorithms you want to revisit • Big-O Quiz mode for spaced practice before interviews

DESIGNED FOR INTERVIEW PREP Whether you are warming up for a coding round, picking the right data structure for a hot loop, or refreshing concepts before a system design call, Lichen stays out of the way and surfaces the answer in two taps.

PRIVACY No tracking. No accounts. Your bookmarks live on your device.