leetcode——226. 翻转二叉树

class Solution:
    def invertTree(self, root: TreeNode) -> TreeNode:
        if not root:
            return root
        def helper(node):
            if node:
                if node.left or node.right:
                    node.left,node.right=node.right,node.left
                helper(node.left)
                helper(node.right)
        helper(root)
        return root

执行用时 :48 ms, 在所有 python3 提交中击败了47.66%的用户

内存消耗 :13.9 MB, 在所有 python3 提交中击败了5.24%的用户

 

——2019.11.19

 

---

public TreeNode invertTree(TreeNode root) {
        if(root == null) return null;
        TreeNode temp = root.left;
        root.left = root.right;
        root.right = temp;
        invertTree(root.left);
        invertTree(root.right);
        return root;
    }

递归