View Code of Problem 1094

#include <cstdio>
#include <cstring>
#include <cmath>
#include <map>
#include <set>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

#define N 100005

struct st
{
    long long x,y;
}a[N];

long long a1[N],a2[N];

bool cmp(const struct st &a,const struct st &b)//与要排序的变量类型一致
{
     return a.x<b.x;
}

int main()
{
    freopen("a","r",stdin);

    long long n,c,i;
    long long f;

    scanf("%lld%lld%lld",&n,&c,&f);
    for (i=1;i<=c;i++) scanf("%lld%lld",&a[i].x,&a[i].y);
    sort(a+1,a+c+1,cmp);

    if (n==1)
    {
        long long j1=-1;
        for (i=1;i<=c;i++)
        if (a[i].y<=f) j1=a[i].x;
        printf("%lld\n",j1);
        return 0;
    }

    multiset<long long>p;
    long long m,m1;
    multiset<long long>::iterator it;

    p.clear();
    m=0;
    for (i=1;i<=c-n/2;i++)
    if (i<=n/2)
    {
        p.insert(a[i].y);
        m+=a[i].y;
        a1[i]=m;
    }
    else
    {
        it=p.end();
        it--;
        m1=*it;

        if (a[i].y<m1)
        {
            m=m-m1+a[i].y;
            p.erase(it);
            p.insert(a[i].y);
        }

        a1[i]=m;
    }

    p.clear();
    m=0;
    multiset<long long>::iterator it1;
    for (i=c;i>=n/2+1;i--)
    if (i>=c-n/2+1)
    {
        p.insert(a[i].y);
        m+=a[i].y;
        a2[i]=m;
    }
    else
    {
        it1=p.end();
        it1--;
        m1=*it1;

        if (a[i].y<m1)
        {
            m=m-m1+a[i].y;
            p.erase(it1);
            p.insert(a[i].y);
        }

        a2[i]=m;
    }

    long long j=-1;
    for (i=c-n/2;i>=n/2+1;i--)
    if (a1[i-1]+a[i].y+a2[i+1]<=f)
    {
        j=a[i].x;
        break;
    }

    cout<<j<<endl;

    return 0;
}

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