226.Invert Binary Tree
===

###### tags: `Easy`,`Tree`,`BFS`,`DFS`,`Binary Tree`

[226. Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree/)

### 題目描述

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

### 範例

**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: []

**Constraints**:

* The number of nodes in the tree is in the range `[0, 100]`.
* -100 <= `Node.val` <= 100

### 解答
#### Python

class Solution:
    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
        if not root: return
        root.left, root.right = self.invertTree(root.right), self.invertTree(root.left)
        return root

> [name=Ron Chen][time=Sat, Feb 18, 2023]

#### Javascript

function invertTree(root) {
  if (root === null) return null;

  const queue = [root];
  while (queue.length) {
    const node = queue.shift();
    const temp = node.left;
    node.left = node.right;
    node.right = temp;
    if (node.left) queue.push(node.left);
    if (node.right) queue.push(node.right);
  }

  return root;
}

> [name=Marsgoat][time=Feb 20, 2023]

### Reference

https://twitter.com/mxcl/status/608682016205344768

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