1.10 05:分数线划定-526互联

错误代码：

#include<bits/stdc++.h>
using namespace std;

struct person{
    int k;
    int s;
}a[10001];

bool cmp(person l,person b)
{
    if(l.s == b.s){
        if(l.k < l.s){
            return false;
        }
        else{
            return true;
        }
    }
    else if(l.s > b.s){
        return true;
    }
    else{
        return false;
    }
}

int main()
{
    int m,n,t,sum = 0,fen;
    double m1;
    scanf("%d %d",&n,&m);
    for(int i = 1;i <= n;++ i){
        scanf("%d %d",&a[i].k,&a[i].s);
    }
    sort(a + 1,a + n + 1,cmp);    
    m1 = double(m) * 1.5;
    m = int(floor(m1));
    fen = a[m].s;
    printf("%d",fen);
    for(int i = 1;a[i].s >= fen;++ i){
        ++ sum;
    }
    printf(" %d",sum);
    for(int i = 1;a[i].s >= fen;++ i){
        printf("\n%d %d",a[i].k,a[i].s);
    }
    return 0;
}

主要是在写cmp函数的时候，没有想通这个到底是干啥的，导致排序的时候会出现混乱。其实就是检测分数相等时，返回序号小的，也就是按照序号小的排。

正确代码：

#include<bits/stdc++.h>
using namespace std;

struct person{
    int k;
    int s;
}a[10001];

bool cmp(person l,person b)
{
    if(l.s != b.s){
        return l.s > b.s; 
    }
    else{
        return l.k < b.k;
    }
}

int main()
{
    int m,n,sum = 0,fen;
    double m1;
    scanf("%d %d",&n,&m);
    for(int i = 1;i <= n;++ i){
        scanf("%d %d",&a[i].k,&a[i].s);
    }
    sort(a + 1,a + n + 1,cmp);    
    m1 = double(m) * 1.5;
    m = int(floor(m1));
    fen = a[m].s;
    printf("%d",fen);
    for(int i = 1;a[i].s >= fen;++ i){
        ++ sum;
    }
    printf(" %d",sum);
    for(int i = 1;a[i].s >= fen;++ i){
        printf("\n%d %d",a[i].k,a[i].s);
    }
    return 0;
}