洛谷P1068 分数线划定

https://www.luogu.org/problem/P1068

#include<bits/stdc++.h>
using namespace std;
struct Can {
    int num;
    int score;
} can[5001];
bool compare1(Can a, Can b) {
    return a.score > b.score;
}
bool compare2(Can a, Can b) {
    return a.num < b.num;
}
int n, m;
int mline, mscore;
int head = 0, tail = 1, mid;
int main() {
    cin >> n >> m;
    for (int i = 0; i < n; i++)
        cin >> can[i].num >> can[i].score;
    sort(can, can + n, compare1);  //按成绩排序  从大到小
    mline = floor(1.5*m);  //floor取不大于x的最大整数   人数 
    mscore = can[mline - 1].score;  //面试成绩   因为从0开始的，所以要减一 
    for (int i = floor(1.5*m); i < n; i++)   //查看往后是否存在相同的成绩 
        if (can[i].score == mscore)  //如果存在，加一 
            mline++;          //计算面试总人数
    mid = can[0].score;
    for (int i = 1; i <= mline; i++) {
        if (can[i].score != mid) {   //判断成绩是否相同
            sort(can + head, can + tail + head, compare2);    //如果没有相同的，相当于给自己排序
            head = head + tail;    //排头相加
            tail = 1;           //如果重新开始，要重新定义的。
            mid = can[head].score;   //重新定义排头
        } else tail++;    //当相同的时候，tail++，然后给相同的按编号排序
    }
    cout << mscore << " " << mline << endl;
    for (int i = 0; i < mline; i++)
        cout << can[i].num << " " << can[i].score << endl;
    return 0;
}