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76 lines
1.1 KiB
Markdown
76 lines
1.1 KiB
Markdown
# [226. Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree/)
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## 题目
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Invert a binary tree.
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**Example**:
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Input:
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```
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4
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/ \
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2 7
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/ \ / \
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1 3 6 9
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```
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Output:
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```
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4
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/ \
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7 2
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/ \ / \
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9 6 3 1
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```
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Trivia:
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This problem was inspired by this original tweet by Max Howell:
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>Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so f*** off.
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## 题目大意
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"经典"的反转二叉树的问题。
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## 解题思路
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还是用递归来解决，先递归调用反转根节点的左孩子，然后递归调用反转根节点的右孩子，然后左右交换根节点的左孩子和右孩子。
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## 代码
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```go
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package leetcode
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/**
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* Definition for a binary tree node.
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* type TreeNode struct {
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* Val int
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* Left *TreeNode
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* Right *TreeNode
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* }
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*/
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func invertTree(root *TreeNode) *TreeNode {
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if root == nil {
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return nil
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}
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invertTree(root.Left)
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invertTree(root.Right)
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root.Left, root.Right = root.Right, root.Left
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return root
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}
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``` |