If you've ever lost 20 minutes at 2 AM debugging a submask enumeration loop, or drawn a segment tree on paper for the fifth time this month, this post is for you.
I want to share a collection of 31 free, browser-based tools built specifically for competitive programming — no signup, no installs, code stays client-side. They're grouped at Utility Tools Lab's Competitive Programming category, and they cover almost every "I wish there was a tool for this" moment from contest practice.
Here's a tour of what's inside.
Visualizing structures you normally only imagine
Half the pain in CP isn't the algorithm — it's seeing what your data structure is actually doing.
