Recursion & the Call Stack: Fibonacci vs Factorial

This simulation explores the fundamental concepts of algorithms by making one of the trickiest to build intuition for — recursion — visible call by call. A real recursive JavaScript function computes Fibonacci numbers (or factorials) while every call and return it makes is logged in order, then replayed as two linked 3D views: a growing recursion tree where each node is one function call, and a call stack column that pushes a frame on every call and pops one on every return, exactly as it happens inside a real interpreter. A memoization toggle demonstrates, with live call-count and cache-hit readouts, how caching repeated sub-problems collapses an exponential-time recursion into a linear one — one concrete algorithmic approach among the many this simulator's broader catalogue tackles.