题目不多说了.见https://oj.leetcode.com/problems/word-ladder-ii/ 这一题我反复修改了两天半.尝试过各种思路,总是报TLE.终于知道这一题为什么是leetcode上通过率最低的一道题了,它对时限的要求实在太苛刻了. 在我AC版本代码的前一个版本,最好也就过了单词长度为7的test case.然后就TLE了. 到底问题在哪儿?我从算法,STL数据结构,代码优化各种角度思考.比较可惜的是,直到最后我也没有弄清为啥能AC,为啥会TLE.(都是我写的代码,都…

Problem Link: http://oj.leetcode.com/problems/word-ladder-ii/ Basically, this problem is same to Word Ladder I, which uses a double-direction BFS. However, the difference is that we need to keep track of all paths during the double-direction BFS in o…

1. Word Search Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or vertically neighboring. The same letter cel…

题目如下: 解题思路:DFS或者BFS都行.本题的关键在于减少重复计算.我采用了两种方法:一是用字典dic_ladderlist记录每一个单词可以ladder的单词列表:另外是用dp数组记录从startword开始到wordlist每一个word的最小转换次数,这一点非常重要,可以过滤很多无效的运算. 代码如下: class Solution(object): def getLadderList(self, w,d): l = [] r = [] for i in xrange(26): l.a…

1. Permutations Given a collection of distinct numbers, return all possible permutations. For example,[1,2,3] have the following permutations: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1] ]  思路:直接使用递归来遍历即可,因为数字是不重复的所以,所以这里的每层递归都从索引0开始遍历整个数组…

Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words. For example, givens = "leetcode",dict = ["leet", "code"]. Return true because &…

Word Ladder II 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 timeEach intermediate word must exist in the dictionaryFor example, Given…

[leetcode]Word Ladder II @ Python 原题地址:http://oj.leetcode.com/problems/word-ladder-ii/ 参考文献:http://blog.csdn.net/doc_sgl/article/details/13341405   http://chaoren.is-programmer.com/ 题意:给定start单词,end单词,以及一个dict字典.要求找出start到end的所有最短路径,路径上的每个单词都要出现在dict…

Word Ladder II 题解 原创文章,拒绝转载 题目来源:https://leetcode.com/problems/word-ladder-ii/description/ Description Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord to endWord, such…

LeetCode解题报告:Linked List Cycle && Linked List Cycle II 1题目 Linked List Cycle Given a linked list, determine if it has a cycle in it. Follow up: Can you solve it without using extra space? Linked List Cycle II Given a linked list, return the node w…