226. Invert Binary Tree
提交网址: https://leetcode.com/problems/invert-binary-tree/
Total Accepted: 84040 Total Submissions: 186266 Difficulty: Easy ACrate:45.1%
Invert a binary tree.
4 / \ 2 7 / \ / \ 1 3 6 9
to
4 / \ 7 2 / \ / \ 9 6 3 1
Trivia: This problem was inspired by this original tweet by Max Howell:
Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.
AC代码:
#include<cstdio>
#include<iostream>
using namespace std;
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* p;
p=root->left;
root->left=root->right;
root->right=p; // 和实现两个变量的交换接近
invertTree(root->left);
invertTree(root->right);
return root;
}
};
// 以下为验证
/*
int main() {
TreeNode *root = new TreeNode(-1);
TreeNode *temp;
root->left = new TreeNode(2);
root->right = new TreeNode(3);
root->right->right = new TreeNode(0);
Solution sol;
cout << root->left->val << endl;
temp=sol.invertTree(root);
cout << temp->left->val << endl;
cout << temp->left->left->val << endl;
return 0;
}*/
在线测试是以满二叉树为例的(总的结点数需要为:2n -1,比如下图以3个为例...)