Solution131.java

import java.util.ArrayList;
import java.util.List;

/**
 * Created by slade on 2019/6/26.
 */
public class Solution131 {
 List<List<String>> ans = new ArrayList<>();

 public List<List<String>> partition(String s) {
 List<String> ansValue = new ArrayList<>();
 if (s == "" || s.length() == 0) {
 return ans;
 }
 subPartition(s, 0, ansValue);
 return ans;
 }

 public void subPartition(String s, int index, List<String> ansValue) {
 if (s.length() == index) {
 ans.add(ansValue);
 return;
 }

 for (int i = index + 1; i <= s.length(); ++i) {
 if (isPalindrome(s.substring(index, i))) {
 ansValue.add(s.substring(index, i));
 //已经用ansValue用的是内存地址，时刻在变，所以要new ArrayList<String>(ansValue)固定值使其不变
 subPartition(s, i, new ArrayList<>(ansValue));

 //因为每次执行subPartition会额外add一个其他元素，当所有结果尝试完成或者不满足要求的时候，需要进行回溯把迭代多少次额外加的元素全部剔除
 ansValue.remove(ansValue.size() - 1);

 }
 }
 }


 public boolean isPalindrome(String s) {
 if (s == "" || s.length() == 0) {
 return false;
 }

 //前缀是否回文
 for (int j = 0; j < s.length() / 2; j++) {
 if (s.charAt(j) != s.charAt(s.length() - j - 1)) {
 return false;
 }
 }
 return true;

 }

 public static void main(String[] args) {
 String s = "abc";
 Solution131 obj = new Solution131();
 System.out.println(obj.partition(s));
 }
}