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# 226. Invert Binary Tree

## 題目 :

Given the root of a binary tree, invert the tree, and return its root.

### Example :

Note

Example 1:

Input: root = [4,2,7,1,3,6,9] Output: [4,7,2,9,6,3,1]

Example 2:

Input: root = [2,1,3] Output: [2,3,1]

Example 3:

Input: root = [] Output: []

#### 解題思路 :

• 這題屬於binary tree的基本題，直接照著邏輯作即可!

### 我的解法

• time complexity: O(n) , space complexity: O(1)

Runtime: 0 ms, faster than 100.00% of Go online submissions for Invert Binary Tree.

 `````` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 `````` ``````/** * Definition for a binary tree node. * type TreeNode struct { * Val int * Left *TreeNode * Right *TreeNode * } */ func invertTree(root *TreeNode) *TreeNode { if root == nil { return root } var Invert func(node *TreeNode) Invert = func(node *TreeNode) { if node.Left != nil { Invert(node.Left) } if node.Right != nil { Invert(node.Right) } node.Left, node.Right = node.Right, node.Left } Invert(root) return root } ``````