Word Ladder II
Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord toendWord, such that:
- Only one letter can be changed at a time
- Each intermediate word must exist in the word list
For example,
Given:
beginWord = "hit"
endWord = "cog"
wordList = ["hot","dot","dog","lot","log"]
Return
[
["hit","hot","dot","dog","cog"],
["hit","hot","lot","log","cog"]
]
Note:
- All words have the same length.
- All words contain only lowercase alphabetic characters.
class Solution {
public:
vector<vector<string> > findLadders(string start, string end,
const unordered_set<string> &dict) {
unordered_set < string > visited; // 判重
unordered_map<string, vector<string> > father; // 树
unordered_set<string> current, next; // 当前层,下一层,用集合是为了去重
bool found = false;
current.insert(start);
visited.insert(start);
while (!current.empty() && !found) {
for (auto word : current){
visited.insert(word);
}
for (auto word : current) {
for (size_t i = ; i < word.size(); ++i) {
string new_word = word;
for (char c = 'a'; c <= 'z'; ++c) {
if (c == new_word[i])
continue;
swap(c, new_word[i]);
if (new_word == end)
found = true; //找到了
if (visited.count(new_word) ==
&& (dict.count(new_word) || new_word == end)) {
next.insert(new_word);
father[new_word].push_back(word);
}
swap(c, new_word[i]); // restore
}
}
}
current.clear();
swap(current, next);
}
vector < vector<string> > result;
if (found) {
vector < string > path;
buildPath(father, path, start, end, result);
}
return result;
}
private:
void buildPath(unordered_map<string, vector<string> > &father,
vector<string> &path, const string &start, const string &word,
vector<vector<string> > &result) {
path.push_back(word);
if (word == start) {
result.push_back(path);
reverse(result.back().begin(),result.back().end());
} else {
for (auto f : father[word]) {
buildPath(father, path, start, f, result);
path.pop_back();
}
}
}
};
Word Ladder II的更多相关文章
- 【leetcode】Word Ladder II
Word Ladder II Given two words (start and end), and a dictionary, find all shortest transformation ...
- 18. Word Ladder && Word Ladder II
Word Ladder Given two words (start and end), and a dictionary, find the length of shortest transform ...
- LeetCode :Word Ladder II My Solution
Word Ladder II Total Accepted: 11755 Total Submissions: 102776My Submissions Given two words (start ...
- [leetcode]Word Ladder II @ Python
[leetcode]Word Ladder II @ Python 原题地址:http://oj.leetcode.com/problems/word-ladder-ii/ 参考文献:http://b ...
- LeetCode: Word Ladder II 解题报告
Word Ladder II Given two words (start and end), and a dictionary, find all shortest transformation s ...
- [Leetcode Week5]Word Ladder II
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/ Descripti ...
- 126. Word Ladder II(hard)
126. Word Ladder II 题目 Given two words (beginWord and endWord), and a dictionary's word list, find a ...
- leetcode 127. Word Ladder、126. Word Ladder II
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 ...
- [LeetCode] Word Ladder II 词语阶梯之二
Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from ...
- [Leetcode][JAVA] Word Ladder II
Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from ...
随机推荐
- VSS Plugin配置FAQ(翻译)[转]
前言(译者) 就个人的成长历程来说,刚参加工作用的是 CVS ,前前后后有接近三年的使用体验,从今年开始使用 SVN .总的来说我更喜欢 SVN ,用起来的确很方便,例如在本地源代码文件中加一个空格然 ...
- CentOS Hadoop格式化HDFS异常java.net.UnknownHostException
#bin/hadoop namenode -format DEPRECATED: Use of this script to execute hdfs command is deprecated. I ...
- 键盘控制select选项上下
$('#k').live('keydown',function(event){ if (event.keyCode==38){ /*$(this).addClass("active" ...
- NOIP2010解题报告
今天状态不错..1个小时AC了前3题,第四题第一次也拿到了80%的分数,后来换了算法才拿到全部分数.. 第一题: 小晨的电脑上安装了一个机器翻译软件,他经常用这个软件来翻译英语文章. 这个翻译软件的原 ...
- Oracle性能调优
这部分目前主要是从网上搜集来的,后续要在实践中慢慢体会. v$sqltext: 存储的是被分割的sql v$sqlarea: 存储的是完整的sql和一些统计信息,比如累计的执行次数.逻辑读.物理读等( ...
- python处理url中的中文编码,以及其他编码问题
1.python中的urlencode与urldecode 2.各种编码转换在线工具 3.python用于url解码和中文解析的小脚本(python url decoder) 4.如何只对url中的中 ...
- poj1274 二分匹配
今天复习二分匹配,A 了一道模板题. 二分匹配需要理解增广路的寻找.用dfs来更新最大匹配.注意一些点:赋初值:愚蠢地把==写成了= ; 然后match的记值;每个点都要重新走一遍. #include ...
- FG模型
一直没搞懂CvBGStatModel和CvFGDStatModel有什么区别.CvBGStatModel模型的创建用cvCreateGaussianBGModel,CvFGDStatModel模型的创 ...
- SharePoint 2013 Nintex Workflow 工作流帮助(四)
博客地址 http://blog.csdn.net/foxdave 接上篇点击打开链接 我们来看下一个配置标签Ribbon Option: Task Notification(用于配置分配任务时的提醒 ...
- UIViewController
UIViewController 在MVC模式中就是C.关于MVC,可以看 UIViewController 主要具有什么功能呢? View Management When you define a ...