Hot100: Permutations (used[] Backtracking ACERS Guide)
Subtitle / Summary If Subsets teaches the skeleton of combination-style backtracking, Permutations teaches the core of state-based backtracking: at each position, choose one unused element, continue until the path length reaches n, and only then collect the answer. Reading time: 10-12 min Tags: Hot100, backtracking, permutations, DFS SEO keywords: Permutations, backtracking, used array, DFS, LeetCode 46 Meta description: Learn the stable permutation backtracking template for LeetCode 46, with state recovery, engineering analogies, and runnable multi-language solutions. Target Readers Hot100 learners who have already finished 78. Subsets and want the next backtracking template Developers who understand recursion but still make mistakes when restoring state Engineers who need to enumerate execution orders, test sequences, or ordering-sensitive plans Background / Motivation The key difference between combinations and permutations is simple: ...