2.用C++完成两种排序算法： 建立10000个随机整数数组，排序后输出排序结果。 排序算法：选择排序，冒泡排序，插入排序，计数排序，基数排序，快速排序，归并排序，堆排序，桶排序，希尔排序，锦标赛排序

下面是选择排序和快速排序的C++代码实现：

1. 选择排序

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

void selection_sort(int arr[], int n) {
    int i, j, min_idx;
    for (i = 0; i < n-1; i++) {
        min_idx = i;
        for (j = i+1; j < n; j++) {
            if (arr[j] < arr[min_idx]) {
                min_idx = j;
            }
        }
        swap(arr[i], arr[min_idx]);
    }
}

int main() {
    srand(time(NULL));
    int n = 10000;
    int arr[n];
    for (int i = 0; i < n; i++) {
        arr[i] = rand();
    }
    selection_sort(arr, n);
    for (int i = 0; i < n; i++) {
        cout << arr[i] << " ";
    }
    cout << endl;
    return 0;
}

2. 快速排序

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

int partition(int arr[], int low, int high) {
    int pivot = arr[high];
    int i = low - 1;
    for (int j = low; j <= high-1; j++) {
        if (arr[j] < pivot) {
            i++;
            swap(arr[i], arr[j]);
        }
    }
    swap(arr[i+1], arr[high]);
    return (i+1);
}

void quick_sort(int arr[], int low, int high) {
    if (low < high) {
        int pi = partition(arr, low, high);
        quick_sort(arr, low, pi-1);
        quick_sort(arr, pi+1, high);
    }
}

int main() {
    srand(time(NULL));
    int n = 10000;
    int arr[n];
    for (int i = 0; i < n; i++) {
        arr[i] = rand();
    }
    quick_sort(arr, 0, n-1);
    for (int i = 0; i < n; i++) {
        cout << arr[i] << " ";
    }
    cout << endl;
    return 0;
}