Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from start to end, such that: Only one letter can be changed at a time    Each intermediate word must exist in the dictionary For example, Given:start = "…

题目: Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord to endWord, such that: Only one letter can be changed at a time Each transformed word must exist in the word list.…

Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord to endWord, such that: Only one letter can be changed at a time Each transformed word must exist in the word list. Note…

Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord to endWord, such that: Only one letter can be changed at a time Each transformed word must exist in the word list. Note…

Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord to endWord, such that: Only one letter can be changed at a time Each intermediate word must exist in the word list For…

原题地址 既然是求最短路径,可以考虑动归或广搜.这道题对字典直接进行动归是不现实的,因为字典里的单词非常多.只能选择广搜了. 思路也非常直观,从start或end开始,不断加入所有可到达的单词,直到最终到达另一端.本质上广度优先遍历图. 需要注意的是,拓展下一个单词时不能对字典进行枚举,因为字典里的单词太多.幸好单词本身都不长,所以直接枚举单词所有可能的变形,看看在dict中出现没有. 当然还不止这些,上面的做法仍然会超时,需要添加剪枝策略: 1. 如果某个单词在以前遍历过了,那么以后都不用再考…

https://leetcode.com/problems/word-ladder-ii/ Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord to endWord, such that: Only one letter can be changed at a time Each inte…

127. Word Ladder 这道题使用bfs来解决,每次将满足要求的变换单词加入队列中. wordSet用来记录当前词典中的单词,做一个单词变换生成一个新单词,都需要判断这个单词是否在词典中,不在词典中就不能加入队列. pathCnt用来记录遍历到的某一个词使用的次数,做一个单词变换生成一个新单词,都需要判断这个单词是否在pathCnt中,如果在,则说明之前已经达到过,这次不用再计算了,因为这次计算的path肯定比之前多.pathCnt相当于剪枝. class Solution { pub…

126. Word Ladder II 题目 Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord to endWord, such that: Only one letter can be changed at a time Each transformed word must exist…

LeetCode:路径总和II[113] 题目描述 给定一个二叉树和一个目标和,找到所有从根节点到叶子节点路径总和等于给定目标和的路径. 说明: 叶子节点是指没有子节点的节点. 示例:给定如下二叉树,以及目标和 sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 返回: [ [5,4,11,2], [5,8,4,5] ] 题目分析 首先是一个深度搜索,来把所有根节点到叶子节点的路径找出来,然后各自判断是否等于目标值,等于目标值的路径加入结果集中.这…