题意

很迷，自行看题。

题解

看懂题就会做了

代码

#include<iostream>
#include<cstring>
#include<algorithm>
#define MAX_N 100005
using namespace std;

int n,s;

struct exchange {
public:
    bool ty;
    int p, q;
    double sp;

    exchange(bool t, int pp, int qq) : ty(t), p(pp), q(qq), sp((double) p / q) { }

    exchange() { }
};

bool cmp(exchange a,exchange b) {
    if (a.ty == b.ty) {
        if (a.ty)return a.p > b.p;
        else return a.p < b.p;
    }
    return a.ty < b.ty;
}

int buy[MAX_N];
int sell[MAX_N];

exchange E0[MAX_N],E1[MAX_N];
int tot0,tot1;

bool cmp0(exchange a,exchange b){
    return a.p>b.p;
}

int main(){
    cin.sync_with_stdio(false);
    cin>>n>>s;
    for(int i=0;i<n;i++){
        char t;
        int p,q;
        cin>>t>>p>>q;
        if(t=='B')buy[p]+=q;
        else sell[p]+=q;
    }
    for(int i=0;i<MAX_N;i++)
        if(sell[i])
            E0[tot0++]=exchange(0,i,sell[i]);
    for(int i=0;i<MAX_N;i++)
        if(buy[i])
            E1[tot1++]=exchange(1,i,buy[i]);
    sort(E0,E0+tot0,cmp);
    sort(E1,E1+tot1,cmp);
    sort(E0,E0+min(s,tot0),cmp0);
    sort(E1,E1+min(s,tot1),cmp0);
    for(int i=0;i<min(s,tot0);i++)cout<<"S "<<E0[i].p<<" "<<E0[i].q<<endl;
    for(int i=0;i<min(s,tot1);i++)cout<<"B "<<E1[i].p<<" "<<E1[i].q<<endl;
    return 0;
}