Z字形打印二叉树

题目链接

/*** 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:vector<vector<int>> levelOrder(TreeNode* root) {vector<vector<int>> res;if(!root) return res;int flag = 0;queue<TreeNode*>que;que.push(root);while(!que.empty()){int n = que.size();vector<int>nums;while(n--){auto tem = que.front();que.pop();nums.push_back(tem->val);if(tem->left) que.push(tem->left);if(tem->right) que.push(tem->right);}if(flag % 2 == 1){reverse(nums.begin(),nums.end());}res.push_back(nums);flag++;}return res;}
};

选择排序

#include <iostream>
using namespace std;void selectionSort(int arr[], int n) {for (int i = 0; i < n-1; i++) {int minIndex = i;for (int j = i+1; j < n; j++) {if (arr[j] < arr[minIndex]) {minIndex = j;}}// 交换arr[i]和arr[minIndex]int temp = arr[i];arr[i] = arr[minIndex];arr[minIndex] = temp;}
}int main() {int arr[] = {64, 34, 25, 12, 22, 11, 90};int n = sizeof(arr)/sizeof(arr[0]);selectionSort(arr, n);cout << "Sorted array: \n";for (int i=0; i < n; i++) {cout << arr[i] << " ";}return 0;
}

冒泡排序

#include <iostream>
using namespace std;void bubbleSort(int arr[], int n) {for (int i = 0; i < n-1; i++) {for (int j = 0; j < n-i-1; j++) {if (arr[j] > arr[j+1]) {// 交换arr[j]和arr[j+1]int temp = arr[j];arr[j] = arr[j+1];arr[j+1] = temp;}}}
}int main() {int arr[] = {64, 34, 25, 12, 22, 11, 90};int n = sizeof(arr)/sizeof(arr[0]);bubbleSort(arr, n);cout << "Sorted array: \n";for (int i=0; i < n; i++) {cout << arr[i] << " ";}return 0;
}