139.单词拆分

class Solution {
    public boolean wordBreak(String s, List<String> wordDict) {
        Set<String> wordDictSet=new HashSet<>(wordDict);   //定义一个集合
        boolean[] dp=new boolean[s.length()+1];            //定义一个动态规划数组
        dp[0]=true;
        for(int i=1;i<=s.length();i++){                    //定义n位动态数组
            for(int j=0;j<i;j++){
                if(dp[j]&&wordDictSet.contains(s.substring(j,i))){
                    dp[i]=true;
                    break;
                }
            }
        }
        return dp[s.length()];
    }
}