symmetric_tree.py

# Symmetric Tree

class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

class Solution(object):
    def isSymmetric(self, root):
        queue = [root.left, root.right]
        
        while queue:
            left_node = queue.pop(0)
            right_node = queue.pop(0)
            
            if not left_node and not right_node:
                continue
            if not left_node or not right_node:
                return False
            if left_node.val != right_node.val:
                return False
            
            queue.append(left_node.left)
            queue.append(right_node.right)
            queue.append(left_node.right)
            queue.append(right_node.left)
        
        return True
 
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(2)
root.left.left = TreeNode(3)
root.left.right = TreeNode(4)
root.right.left = TreeNode(4)
root.right.right = TreeNode(3)

solution = Solution()
print(solution.isSymmetric(root))