leetcode-solutions/226. Invert Binary Tree/invert-binary-tree.py3 at master · fcaponetto/leetcode-solutions · GitHub

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# 226. Invert Binary Tree (2/20/56549)
# Runtime: 40 ms (17.13%) Memory: 16.57 MB (0.00%)

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
        frontier = deque()
        if root:
            frontier.append(root)

        while frontier:
            for _ in range(len(frontier)):
                curr = frontier.popleft()

                print(curr)
                left = curr.left
                right = curr.right
                if left:
                    frontier.append(left)
                if right:
                    frontier.append(right)

                curr.right = left
                curr.left = right


        return root