131. 分割回文串

给定一个字符串 s，将 s 分割成一些子串，使每个子串都是回文串。

返回 s 所有可能的分割方案。

示例:

输入: "aab"
输出:
[
["aa","b"],
["a","a","b"]
]

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/palindrome-partitioning
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

public class Solution {
    private char[] s = null;

    // 返回i位置开始k(k>j)位置结束的回文串的结束位置k
    private int nextLoc(int i, int j) {
        int l = -1, m, n;
        for (l = j+1; l < s.length; l++) {
            for (m = i, n = l; m < n; m++, n--) {
                if (s[m] != s[n])
                    break;
            }
            if (m >= n)
                return l;
        }
        return (l == s.length) ? -1 : l;
    }

    private void helper(int cur,List<String> subset, List<List<String>> res){
        if (cur == s.length) {
            res.add(new ArrayList<>(subset));
            return;
        }

        for (int i = cur, j = cur; j != -1; ) {
            subset.add(String.valueOf(s, i, j-i+1));
            helper(j+1,subset, res);
            subset.remove(subset.size()-1);
            j = nextLoc(i,j);
        }
    }

    public List<List<String>> partition(String s) {
        this.s = s.toCharArray();
        List<String> subset = new ArrayList<>();
        List<List<String>> res = new ArrayList<>();
        helper(0,subset, res);
        return res;
    }

    public static void main(String[] args) {
        Solution solution = new Solution();
        List<List<String>> abaaab = solution.partition("abaaab");
        for (List<String> e : abaaab) {
            System.out.println(e);
        }
    }
}