257. Binary Tree Paths
Given a binary tree, return all root-to-leaf paths.
Note: A leaf is a node with no children.
Example:
代码语言：javascript复制Input:
1
/
2 3
5
Output: ["1->2->5", "1->3"]
Explanation: All root-to-leaf paths are: 1->2->5, 1->3思路：
题目意思是从root节点走到叶子节点一共有多少路径，采用递归求解，和先序遍历类似，找到叶子节点就把路径保存下来。
代码：
go：
代码语言：javascript复制/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func binaryTreePaths(root *TreeNode) []string {
var res []string
if root == nil {
return res
}
recursive(root, &res, strconv.Itoa(root.Val) "->")
return res
}
func recursive(node *TreeNode, res *[]string, s string) {
if node.Left == nil && node.Right == nil {
*res = append(*res, s[:len(s)-2])
}
if node.Left != nil {
recursive(node.Left, res, s strconv.Itoa(node.Left.Val) "->")
}
if node.Right != nil {
recursive(node.Right, res, s strconv.Itoa(node.Right.Val) "->")
}
}
