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Solution: Word Ladder II

Explore how to solve the Word Ladder II problem by implementing a two-phase strategy that uses BFS to find the shortest transformation paths and DFS backtracking to reconstruct all valid sequences. Understand how to efficiently manage word transformations, avoid cycles, and produce all shortest word sequences between beginWord and endWord.

Statement

You are given two words, beginWord and endWord, and a dictionary of words called wordList. Your task is to find all the shortest transformation sequences from beginWord to endWord, such that:

  1. Only one letter can be changed at a time.

  2. Each transformed word must exist in the given wordList.

  3. The transformation sequence must begin with beginWord and end with endWord.

Return all the shortest transformation sequences as a list of lists. If no valid transformation exists, return an empty list.

Constraints:

  • 11 \leq ...