Palindrome Partitioning

Given a string s, partition s such that every substring of the partition is a palindrome.

Return all possible palindrome partitioning of s.

For example, given s = "aab",
Return

[
  ["aa","b"],
  ["a","a","b"]
]

给定一个指针从字符串从前往后移动，从开头到该指针的字符串是回文，则递归剩下后面部分字符串。

代码如下：

class Solution {
    public List<List<String>> partition(String s) {
        List<List<String>> res=new ArrayList<List<String>>();
        if(s==null||s.length()==0) return res;
        helper(res,new ArrayList<String>(),s,0);
        return res;
    }
    public void helper(List<List<String>> res,List<String> list,String s,int index){
        if(index==s.length()){
            res.add(new ArrayList<String>(list));
            return ;
        }
        for(int i=index;i<s.length();i++){
            String sub=s.substring(index,i+1);
            if(isP(sub)){
                list.add(sub);
                helper(res,list,s,i+1);
                list.remove(list.size()-1);
            }
        }
    }
    public boolean isP(String s){
        StringBuilder sb=new StringBuilder(s);
        return sb.reverse().toString().equals(s);
    }
}