用c语言代码输出n个数的逆序数

以下是一个基于归并排序的算法，可以输出n个数的逆序数：

#include <stdio.h>

int merge(int arr[], int temp[], int left, int mid, int right) {
    int i = left, j = mid, k = left;
    int count = 0;
    while (i <= mid - 1 && j <= right) {
        if (arr[i] <= arr[j]) {
            temp[k++] = arr[i++];
        } else {
            temp[k++] = arr[j++];
            count += mid - i;
        }
    }
    while (i <= mid - 1) {
        temp[k++] = arr[i++];
    }
    while (j <= right) {
        temp[k++] = arr[j++];
    }
    for (i = left; i <= right; i++) {
        arr[i] = temp[i];
    }
    return count;
}

int merge_sort(int arr[], int temp[], int left, int right) {
    int mid, count = 0;
    if (right > left) {
        mid = (right + left) / 2;
        count += merge_sort(arr, temp, left, mid);
        count += merge_sort(arr, temp, mid + 1, right);
        count += merge(arr, temp, left, mid + 1, right);
    }
    return count;
}

int main() {
    int n, arr[100], temp[100], i;
    printf("Enter the number of elements: ");
    scanf("%d", &n);
    printf("Enter the elements: ");
    for (i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }
    int count = merge_sort(arr, temp, 0, n - 1);
    printf("Number of inversions: %d", count);
    return 0;
}

在这个程序中，merge函数用于将两个已排序的子数组合并成一个已排序的数组，并计算逆序数的数量。merge_sort函数使用归并排序算法将数组分成两半，对各半部分递归调用merge_sort函数，并使用merge函数将这两个已排序的半部分合并成一个已排序的数组。最终，merge_sort函数返回逆序数的数量。程序接受用户输入的n个数，并输出逆序数的数量。