题解 | Forsaken给学生分组

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int compare(const void* p1, const void* p2)
{
    long long a = *(long long*)p1;
    long long b = *(long long*)p2;
    if (a > b) return 1;
    else if (a < b) return -1;
    else return 0;
}

int main()
{
    long long n, k;
    scanf("%lld %lld", &n, &k);
    long long arr[n];
    for (int i = 0; i < n; i++) {
        scanf("%lld", &arr[i]);
    }
    qsort(arr, n, sizeof(long long), compare);

    long long num = 0; 
    for (int i = 0; i < k; i++) {
        num += arr[n - i - 1] - arr[i];
    }
    printf("%lld", num);  
    return 0;
}