Recursion

Watch the call stack grow, shrink, and finally make sense.

1. 1Recursion BasicsA function that solves a smaller copy of itself.5m
2. 2The Call StackEvery pending call waits its turn on a stack of frames.5m
3. 3Factorial and FibonacciOne call per step, or two calls that redo everything.6m
4. 4MemoizationWrite each answer down once, never solve it twice.5m
5. 5BacktrackingChoose, explore, then undo the choice and try the next.6m