二叉树镜像

题目链接

递归解法

class Solution:
    def mirrorTree(self, root: TreeNode) -> TreeNode:
        if not root:return root
        self.mirrorTree(root.left)
        self.mirrorTree(root.right)
        root.right,root.left=root.left,root.right
        return root

BFS解法

class Solution:
    def mirrorTree(self, root: TreeNode) -> TreeNode:
        #尝试BFS解法
        if not root:return root
        queue=[root]
        while queue:
            next_queue=[]
            for node in queue:
                node.right,node.left=node.left,node.right
                if node.left:next_queue.append(node.left)
                if node.right:next_queue.append(node.right)
            queue=next_queue
        return root