标签：style blog http color os io ar for 2014
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, given
s = "leetcode",
dict = ["leet", "code"].
Return true because "leetcode" can
be segmented as "leet code".
题意：
给定一个字符串和一个单词字典，判断这个字符串是否可以用字典里的单词来分割
思路：dp
设dp[i] 表示字符串[0,i]的子串是否能被字典里的单词来分割
dp[i] = true ,if 存在0 < k < i 使得 dp[k]为true并且字符串[k + 1,i]在单词字典里；或者 字符串[0,i]本身就在单词字典里。
dp[i] = false , else
复杂度：时间O(n)，空间O(n)
bool wordBreak(string s, unordered_set<string> &dict){
vector<bool> dp(s.size(), false);
for(int i = 0; i < s.size(); ++i){
dp[i] = dict.find(s.substr(0, i + 1)) != dict.end();
if(dp[i]) continue;
for(int k = 0; k < i; ++k){
if(dp[k] && dict.find(s.substr(k + 1, i - k )) != dict.end()) {
dp[i] = true;
break;
}
}
}
return dp[s.size() - 1];
}标签：style blog http color os io ar for 2014
原文地址：http://blog.csdn.net/zhengsenlie/article/details/39160399
