LeetCode-113. Path Sum II

题目描述

Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum.题目及实例

解题思路

该题目与LeetCode-112有着相同的思路，只不过本题目需要将满足条件的路径上所有节点的值输出。

代码

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    List<List<Integer>> result = new LinkedList<List<Integer>>();
    public List<List<Integer>> pathSum(TreeNode root, int sum) {
        if(root==null)
            return result;
        pathSum(root,sum,new LinkedList<Integer>());
        return result;
    }
    public void pathSum(TreeNode root,int sum,List<Integer> tmp){
        if(root == null)
            return;
        if(root.left == null && root.right == null && root.val == sum){
            tmp.add(root.val);//添加当前节点值
            result.add(new LinkedList<Integer>(tmp));
            tmp.remove(tmp.size()-1);//删除当前节点值
            return;
        }
        tmp.add(root.val);//添加当前节点值
        pathSum(root.left,sum-root.val,tmp);
        pathSum(root.right,sum-root.val,tmp);
        tmp.remove(tmp.size()-1);//删除当前节点值
    }
}