Word Break

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 wordBreakHelper(String s,Set<String> dict,HashMap<String,Boolean> ht){
        if (s.length()<1){
            return true;
        }
        boolean flag = false;
        for(int i=0;i<=s.length();i++){
            String temp = s.substring(0,i);
            if (dict.contains(temp)){
                if (ht.get(s.substring(temp.length(),s.length()))!=null){
                    flag =  ht.get(s.substring(temp.length(),s.length()));
                }else{
                    flag = wordBreakHelper(s.substring(temp.length(), s.length()), dict, ht);
                    ht.put(s.substring(temp.length(),s.length()),flag);
                }
            }
            if (flag) {
                return true;
            }
        }
        return false;
    }
    public boolean wordBreak(String s, Set<String> dict) {
        return wordBreakHelper(s, dict, new HashMap<String, Boolean>());
    }
}