leetcode: Word Break

Very basic recursion gives time limit exceeded.

The remedy is: using a hashSet to remember impossible breaking points which have been tried.

public class Solution {
    public boolean wordBreak(String s, Set dict) {
      
       return recursion(s, dict, 0);
    }
    
    public boolean recursion(String s, Set dict, int current){
         if(current == s.length()) return true;//base case
         
         for(int i = s.length(); i>current; i--){
             if(dict.contains(s.substring(current, i)))
             {
                 dict.add(s.substring(0, i));
                 if(recursion(s, dict, i))
                    return true;
             }
         }
         return false;
    }
}