Recursion on the call stack: 5! unwinds
This animation visualizes fact(5) as it pushes five stacked frames, one for each recursive call, until reaching the base case fact(0). It then shows the stack unwinding in reverse, with each frame computing and returning a value: 1, 1, 2, 6, 24, and finally 120. The visual makes clear why deep recursion consumes memory proportional to call depth, helping students connect abstract recursive code to concrete stack behavior and return-value propagation.
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The prompt that made it
fact(5) pushes five frames onto the call stack until the base case, then unwinds computing 1, 2, 6, 24, 120 as each frame returns; deep recursion means many frames of memory.
Make the next one in this series
- Compare the call stack growth of recursive versus iterative factorial implementations side by side
- Show how tail recursion optimization can flatten the call stack for factorial
- Visualize a stack overflow occurring when factorial is called with a very large input
