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website/content/ChapterFour/0257.Binary-Tree-Paths.md

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+# [257. Binary Tree Paths](https://leetcode.com/problems/binary-tree-paths/)
+
+
+## 题目
+
+Given a binary tree, return all root-to-leaf paths.
+
+**Note**: A leaf is a node with no children.
+
+**Example**:
+
+    Input:
+    
+       1
+     /   \
+    2     3
+     \
+      5
+    
+    Output: ["1->2->5", "1->3"]
+    
+    Explanation: All root-to-leaf paths are: 1->2->5, 1->3
+
+## 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
+
+```go
+
+package leetcode
+
+import (
+	"strconv"
+)
+
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func binaryTreePaths(root *TreeNode) []string {
+	if root == nil {
+		return []string{}
+	}
+	res := []string{}
+	if root.Left == nil && root.Right == nil {
+		return []string{strconv.Itoa(root.Val)}
+	}
+	tmpLeft := binaryTreePaths(root.Left)
+	for i := 0; i < len(tmpLeft); i++ {
+		res = append(res, strconv.Itoa(root.Val)+"->"+tmpLeft[i])
+	}
+	tmpRight := binaryTreePaths(root.Right)
+	for i := 0; i < len(tmpRight); i++ {
+		res = append(res, strconv.Itoa(root.Val)+"->"+tmpRight[i])
+	}
+	return res
+}
+
+```