Run uses paiza.io's free guest API (no key, no card). It needs this proxy because paiza.io doesn't allow direct browser calls. Deploy worker.js on Cloudflare Workers — entirely through their web dashboard, no terminal or install needed — then paste the URL it gives you here.
Get a key at aistudio.google.com/apikey. It's kept in memory only, for this session, and sent directly from your browser to Google's API — never stored or sent anywhere else.
Output
Visualize
Run your code to see output here.
Run your code successfully first — Visualize turns a clean run into an animated, step-by-step diagram of how your algorithm moves through its data.