难度中等
输入一棵二叉树和一个整数,打印出二叉树中节点值的和为输入整数的所有路径。从树的根节点开始往下一直到叶节点所经过的节点形成一条路径。
示例:
给定如下二叉树,以及目标和 target = 22,
5
/ \
4 8
/ / \
11 13 4
/ \ / \
7 2 5 1
返回:
[
[5,4,11,2],
[5,8,4,5]
]
提示:
-
节点总数 <= 10000
注意:本题与主站 113 题相同:https://leetcode-cn.com/problems/path-sum-ii/
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
List<List<Integer>> ret = new ArrayList<>();
public List<List<Integer>> pathSum(TreeNode root, int target) {
dfs(new ArrayList<>(),root,target);
return ret;
}
private void dfs(ArrayList<Integer> list, TreeNode root, int target) {
if (root == null){
return;
}
list.add(root.val);
target-=root.val;
if (0==target&&root.left == null &&root.right == null){
ret.add(new ArrayList<>(list));
}else{
dfs(list,root.left,target);
dfs(list,root.right,target);
}
list.remove(list.size()-1);
}
}