题解 | 分数线划定

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

typedef struct{
    int id, score;
}p;

int compare(const void* a, const void* b) {
    const p*ca = (const p*)a;
    const p*cb = (const p*)b;

    if(ca -> score != cb -> score)
        return cb -> score - ca -> score;
    return ca -> id - cb -> id;
}   //从大到小，成绩 -- 小到大，报名号

int main(void) {
    int n, m;
    scanf("%d%d", &n, &m);

    p* np = (p*)malloc(n * sizeof(p));
    for(int i = 0; i < n; i++)
        scanf("%d%d", &np[i].id, &np[i].score);

    qsort(np, n, sizeof(p), compare);

    int k = (int)floor(1.5 * m);
    int line = np[k-1].score;

    int count = 0;
    for(int i = 0; i < n; i++){
        if(np[i].score >= line)
            count++;
        else
            break;
    }

    printf("%d %d\n", line, count);

    for(int i = 0; i < count; i++)
        printf("%d %d\n", np[i].id, np[i].score);

    free(np);
    return 0;
}