leetcode 139. Word Break

Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequence of one or more dictionary words. You may assume the dictionary does not contain duplicate words.

For example, given
s = "leetcode",
dict = ["leet", "code"].

Return true because "leetcode" can be segmented as "leet code".

UPDATE (2017/1/4):
The wordDict parameter had been changed to a list of strings (instead of a set of strings). Please reload the code definition to get the latest changes.

采用动态规划，dp[i]表示目标字符串s中0-i是否合法

public class Solution {
    public boolean wordBreak(String s, List<String> wordDict) {
        boolean[] res = new boolean[s.length() +1];
        res[0] = true;
        for(int i=1; i < s.length()+1; i++){
            for(String str : wordDict){
                if(str.length() <=i){
                    if(res[i-str.length()]){
                        if(s.substring(i-str.length(), i).equals(str)){
                            res[i] = true;
                            break;
                        }
                    }
                }
            }
        }
        return res[s.length()];
    }
}