StackScholar

Tree traversals

easy

The three depth-first orders run the same two recursive calls; all that changes is where `visit` sits. Swap the stack for a queue and depth-first becomes breadth-first.

Worst O(n)Space O(h) for the stack
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Where to go next

Binary search tree

medium

Insert, search and the three cases of deletion.

Depth-first search

easy

A stack instead of a queue - that is the only difference.

Breadth-first search

easy

Expands in rings, so it finds shortest paths.