Recursion and Backtracking Search

Define a recursive function using an explicit state, base case, and progress step.

Trace recursive calls and returns using a call tree.

Estimate the call count, maximum recursion depth, and stack-space cost of a recursive search, including JavaScript stack-overflow risk.

Generate all subsets of a set using choose-or-skip recursion.

Generate all permutations while tracking which choices have already been used.

Generate combinations while preventing duplicate orderings.

Prune a backtracking search as soon as a partial candidate violates a constraint.

Restore mutable state correctly after exploring each backtracking branch.