倒置二叉树

答案：

递归方法

# Definition for a binary tree node.# class TreeNode(object):# def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution(object): def invertTree(self, root): """ :type root: TreeNode :rtype: TreeNode """ if root == None: return None root.right,root.left = self.invertTree(root.left),self.invertTree(root.right) return root

迭代方法：

# Definition for a binary tree node.# class TreeNode(object):#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution(object):    def invertTree(self, root):        """        :type root: TreeNode        :rtype: TreeNode        """        if root==None or root.left==root.right==None: return root        parent = [root]        while len(parent):            children = []            for node in parent:                node.left, node.right = node.right, node.left                if node.left: children.append(node.left)                if node.right: children.append(node.right)            parent = children        return root