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Solution: Word Ladder II

Explore how to implement a two-phase strategy using BFS for shortest path discovery and DFS backtracking to reconstruct all shortest transformation sequences from beginWord to endWord. This method efficiently handles word transformations within given constraints, enabling you to solve complex word ladder problems with optimal time and space complexity.

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 ...