LeetCode Word Break(DFS)

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".

public class Solution {    public boolean wordBreak(String s, Set<String> dict) {        return wordBreakHelper(s, dict, 0);    }        public boolean wordBreakHelper(String s, Set<String> dict, int start)    {        if (start == s.length()) return true;                for (String tmp : dict) {            int len = tmp.length();            int end = start + len;                        if (end > s.length()) continue;                        if (s.substring(start, end).equals(tmp)) {                if (wordBreakHelper(s, dict, end)) return true;            }        }                return false;    }}