Word Break

public class Solution {
    public boolean wordBreak(String s, Set<String> wordDict) {
        int len = s.length();
        boolean[] isValidStart = new boolean[len+1];
        isValidStart[0] = true;

        for(int i = 0; i < len; i++) {
            if(!isValidStart[i]) {
                continue;
            }
            for(int j = i + 1; j <= len; j++) {
                String sub = s.substring(i, j);
                if(wordDict.contains(sub)) {
                    isValidStart[j] = true;
                    if(isValidStart[len]) {
                        return true;
                    }
                }
            }
        }

        return false;
    }
}