257. Binary Tree Paths

🟢   🔖  树 深度优先搜索 字符串 回溯 二叉树  🔗 LeetCode

题目

Given the root of a binary tree, return all root-to-leaf paths in any order.

A leaf is a node with no children.

Example 1:

Input: root = [1,2,3,null,5]

Output: ["1->2->5","1->3"]

Example 2:

Input: root = [1]

Output: ["1"]

Constraints:

• The number of nodes in the tree is in the range [1, 100].
• -100 <= Node.val <= 100

题目大意

给定一个二叉树，返回所有从根节点到叶子节点的路径。说明: 叶子节点是指没有子节点的节点。

解题思路

Google 的面试题，考察递归

代码

/**
 * @param {TreeNode} root
 * @return {string[]}
 */
var binaryTreePaths = function (root) {
	let res = [];
	if (!root) return res;
	if (!root.left && !root.right) return ['' + root.val];
	let tempLeft = binaryTreePaths(root.left);
	for (let i of tempLeft) {
		res.push(root.val + '->' + i);
	}
	let tempRight = binaryTreePaths(root.right);
	for (let i of tempRight) {
		res.push(root.val + '->' + i);
	}
	return res;
};

相关题目

相关题目

• 113. 路径总和 II
• 988. 从叶结点开始的最小字符串
• 2096. 从二叉树一个节点到另一个节点每一步的方向

- [113. 路径总和 II](./0113.md)
- [988. 从叶结点开始的最小字符串](https://leetcode.com/problems/smallest-string-starting-from-leaf)
- [2096. 从二叉树一个节点到另一个节点每一步的方向](https://leetcode.com/problems/step-by-step-directions-from-a-binary-tree-node-to-another)