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2022.04.23 二叉树的所有路径

认真的老去 2022-04-23 阅读 48

题目地址(257. 二叉树的所有路径)

https://leetcode-cn.com/problems/binary-tree-paths/

题目描述

给你一个二叉树的根节点 root ,按 任意顺序 ,返回所有从根节点到叶子节点的路径。

叶子节点 是指没有子节点的节点。

 

示例 1:

输入:root = [1,2,3,null,5]
输出:["1->2->5","1->3"]


示例 2:

输入:root = [1]
输出:["1"]


 

提示:

树中节点的数目在范围 [1, 100] 内
-100 <= Node.val <= 100

前置知识

  • dfs

代码

  • 语言支持:JavaScript

JavaScript Code:


/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {string[]}
 */
var binaryTreePaths = function(root) {
    let path = [];
    let res = [];
    if (root == null) {
        return res;
    }
    dfs(root, path, res);
    return res;
};

function dfs(curr, path, res) {
    path.push(curr.val);
    if (curr.left == null && curr.right == null) {
        res.push(path.join('->'));
        return res;
    }
    if (curr.left) {
        dfs(curr.left, path, res);
        path.pop();
    }
    if (curr.right) {
        dfs(curr.right, path, res);
        path.pop();
    }
}

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