c++弄出随机10个数用选择法对10个整数从大到小排列

在C++中，你可以使用标准库`<cstdlib>`和`<ctime>`来生成随机数，并结合排序算法（如快速选择、堆排序等）对10个整数进行降序排列。这里是一个简单的示例，使用了快速选择作为简化版的排序，因为快速选择对于大型数据集效率较高：

#include <iostream>
#include <vector>
#include <cstdlib> // for rand and srand
#include <ctime>   // for time

// 随机数生成函数
int random_number(int min, int max) {
    return min + static_cast<int>((max - min + 1) * std::rand() / RAND_MAX);
}

// 使用快速选择法选择最大值
int find_max(std::vector<int>& arr, size_t low, size_t high) {
    if (low == high) { // base case: only one element
        return arr[low];
    }

    size_t pivot_index = partition(arr, low, high); // partition the array
    if (pivot_index == high - 1) { // pivot is already at its final place
        return arr[pivot_index];
    } else if (pivot_index < high - 1) {
        return find_max(arr, pivot_index + 1, high); // recur on right partition
    } else {
        return find_max(arr, low, pivot_index); // recur on left partition
    }
}

// Partition function for quickselect
size_t partition(std::vector<int>& arr, size_t low, size_t high) {
    int pivot = arr[high]; // take last element as pivot
    size_t i = low - 1;

    for (size_t j = low; j < high; ++j) {
        if (arr[j] >= pivot) {
            i++;
            std::swap(arr[i], arr[j]);
        }
    }
    std::swap(arr[i + 1], arr[high]); // put pivot in its correct position
    return i + 1;
}

int main() {
    std::srand(std::time(0)); // seed the random number generator

    std::vector<int> numbers(10);
    for (auto& num : numbers) {
        num = random_number(1, 100); // generate a random integer between 1 and 100
    }

    int max_num = find_max(numbers, 0, numbers.size() - 1);
    std::cout << "Sorted numbers (in descending order): ";
    for (const auto& num : numbers) {
        std::cout << num << " ";
    }
    std::cout << "\nMax number: " << max_num << std::endl;

    return 0;
}