MR CodeBlocks is a practice ground for real interview and contest problems — structured tracks, an instant judge in 12 languages, and mock tests that feel like the real thing.
// popular right now
Build core comfort with arrays and strings — from basic traversal to hashing and two-pointer techniques.
Strengthen fundamental math-based problem solving — often the easiest wins in coding interviews if practiced well.
Move from simple recursion to recognizing overlapping subproblems — the foundation of dynamic programming.
Explore how choosing the right data structure — a stack, a sorted array, or a grid — makes problems dramatically simpler.
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Choose a structured path or jump straight to a topic you want to sharpen.
A full Monaco editor, 12 languages, sample tests you can run before you submit.
Pass/fail per test case, runtime, memory — no waiting, no guessing.
// built for practice that counts
Submissions run against real test cases and return verdicts in under a second, on average.
Timed sections and lockdown mode for tests that mirror the real thing.
Earn badges as you clear milestones — a small nudge to keep the streak alive.
Python, C++, Java, Go, Rust, TypeScript and more — solve in whatever you're learning.
// your move
No credit card, no setup — open a problem and start writing code.
Browse tracks →