131. Palindrome Partitioning

class Solution {
    public List<List<String>> partition(String s) {
        List<List<String>> list = new ArrayList();
        List<String> sublist = new ArrayList();
        backtrack(list, sublist, s, 0);
        return list;
    }
    public void backtrack(List<List<String>> list, List<String> sublist, String s, int start){
        if(start==s.length()){
            list.add(new ArrayList(sublist));
            return;
        }
        for(int i = start; i<s.length();i++){
            if(isPalindrome(s, start, i)){
                if(start==i)
                    sublist.add(s.charAt(start)+"");
                else
                    sublist.add(s.substring(start, i+1));
                backtrack(list, sublist, s, i+1);
                sublist.remove(sublist.size()-1);
            }
        }
    }
    public boolean isPalindrome(String s, int low, int high){
        while(low<=high){
            if(s.charAt(low++)!=s.charAt(high--))
                return false;
        }
        return true;
    }
}