139. Word Break

题目

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.

Note:

• The same word in the dictionary may be reused multiple times in the segmentation.
• You may assume the dictionary does not contain duplicate words.

我的想法

感觉是472. Concatenated Words的简单版
一样的方法，用dp就行

class Solution {
    public boolean wordBreak(String s, List<String> wordDict) {
        HashSet<String> dict = new HashSet<>();
        for(String word : wordDict) {
            dict.add(word);
        }
        boolean[] dp = new boolean[s.length() + 1];
        dp[0] = true;
        for(int i = 0; i < s.length(); i++) {
            if(!dp[i]) {
                continue;
            }
            for(int j = i + 1; j <= s.length(); j++) {
                String sub = s.substring(i, j);
                if(dict.contains(sub)) {
                    dp[j] = true;
                }
            }
        }
        if(dp[s.length()]) {
            return true;
        }
        return false;
    }
}

解答