动态分配内存，可根据输入设置数组大小

#include <stdio.h>
#include <iostream>
#include <algorithm>
using namespace std;
void sort(int *score, int *id, int n);
int main()
{
    int n, *id, *score;
    printf("Input number:\n");
    scanf("%d", &n);
    id = (int *)malloc(sizeof(int)*n);
    score = (int *)malloc(sizeof(int)*n);
    printf("Input number, score:\n");
    for (int i = 0; i < n; i++)
    {
        printf("第%d个学生：", i + 1);
        scanf("%d %d", id + i, score + i);
    }
    sort(score, id, n);
    printf("排序后：\n");
    for (int i = 0; i < n; i++)
    {
        printf("第%d个学生", i + 1);
        printf("id:%d\tscore:%d\n", *(id + i), *(score + i));
    }
    return 0;
}
void sort(int *score, int *id, int n)
{
    int i, j, k;
    for(i = 0; i < n-1; i++)
    {
        k = i;
        for(j = k+1; j < n; j++)
        {
            if(score[j] > score[k])
                k = j;
        }
        if(k != i)
        {
            swap(score[i], score[k]);
            swap(id[i], id[k]);
        }
    }
}