LeetCode--word-break-ii

Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word. 

Return all such possible sentences. 

For example, given
s ="catsanddog",
dict =["cat", "cats", "and", "sand", "dog"]. 

A solution is["cats and dog", "cat sand dog"].

参考博文：https://segmentfault.com/a/119000000369869

https://blog.csdn.net/u013395544/article/details/79819242

https://blog.csdn.net/linhuanmars/article/details/22358863

import java.util.*;
public class Solution {
    public ArrayList list = new ArrayList<>();
    public ArrayList wordBreak(String s, Set dict) {
        dfs(s, s.length(), "", dict);
        return list;
    }
 
    private void dfs(String s, int index, String str, Set dict) {
        if (index <= 0) {
            if (str.length() > 0) {
                //存放由单词组成的句子
                list.add(str.substring(0, str.length() - 1));
            }
        }
        for (int i = index; i >= 0; i--) {
            if (dict.contains(s.substring(i, index))) {
                dfs(s, i, s.substring(i, index) + " " + str, dict);
            }
        }
    }
}