题目:
Invert a binary tree.
Example:
Input: 4 / \ 2 7 / \ / \ 1 3 6 9 Output: 4 / \ 7 2 / \ / \ 9 6 3 1
解释:
翻转一颗二叉树。
用一个变量保存原始的一个子树,之后再修改。
python代码:
# 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
else:
temp=root.left
root.left=self.invertTree(root.right)
root.right=self.invertTree(temp)
return root
c++代码:
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
TreeNode* invertTree(TreeNode* root) {
if (root==NULL)
return NULL;
TreeNode *temp=root->left;
root->left=invertTree(root->right);
root->right=invertTree(temp);
return root;
}
};
总结:
注意要保存一下原始的子树。