题解 | #回文数字#

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 * }
 */

public class Solution {
    /**
     * 
     * @param root TreeNode类 
     * @param sum int整型 
     * @return int整型ArrayList<ArrayList<>>
     */
     static ArrayList<ArrayList<Integer>> res =  new ArrayList<ArrayList<Integer>>();//存放结果
    static int  sumNum;
    static   ArrayList<Integer> path = new ArrayList<Integer>();//存放路径
    public ArrayList<ArrayList<Integer>> pathSum (TreeNode root, int sum) {
       sumNum = sum;
        findPath(root,0);
        // write code here
        return res;
    }
    //定义一个集合
    static void findPath(TreeNode root, int temps){

        if(root == null){
            return;
        }
        path.add(root.val);
        temps = temps + root.val;
        if(temps == sumNum && root.left == null && root.right == null){

            res.add(new ArrayList<Integer>(path));//复制一个

            //不然还是不断改变
            path.remove(path.size()-1);
            return;
        }
        if(root.left != null){
             findPath(root.left,temps);
        }

        if(root.right != null){
            findPath(root.right,temps);
        }

            path.remove(path.size()-1);






    }





}