[트리] 리트코드 226: invert binary tree

# https://leetcode.com/problems/invert-binary-tree


# 시작: 2021.05.31 13:50
# 끝: 2021.05.31 23:08

# 루트-오른쪽-왼쪽 순서로 읽는다.

# bfs로 읽어나가며 좌우 반전
class Solution:

    def invertTree(self, root: TreeNode) -> TreeNode:
        q= deque()
        if (root):
            q.append(root)
        
        while q:
            for _ in range(len(q)):
                node = q.popleft()
                tmp = node.left
                node.left = node.right
                node.right = tmp
                
                if node.left:
                    q.append(node.left)
                if node.right:
                    q.append(node.right)
        
        return root