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257. 二叉树的所有路径
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:
1
/ \
2 3
\
5
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
- 来源:力扣(LeetCode)
- 链接:https://leetcode.cn/problems/binary-tree-paths
javascript
/**
* 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) {
var res = []
dfs(root, "")
function dfs(root, str) {
if (!root) return
str += root.val
if (!root.left && !root.right) {
res.push(str)
}
str += "->"
dfs(root.left, str)
dfs(root.right, str)
}
return res
}
// test
function TreeNode(val, left, right) {
this.val = val === undefined ? 0 : val
this.left = left === undefined ? null : left
this.right = right === undefined ? null : right
}
var n1 = new TreeNode(1)
var n2 = new TreeNode(2)
var n3 = new TreeNode(3)
var n4 = new TreeNode(5)
n1.left = n2
n1.right = n3
n2.right = n4
console.log(binaryTreePaths(n1))