poj 2010 Moo University - Financial Aid 大顶堆维护最小和

//poj 2010
//sep9
#include <iostream>
#include <queue>
#include <algorithm>
using namespace std;
const int maxN=100024;

int dpl[maxN],dpr[maxN];
priority_queue<int> Q;

struct Cow
{
	int s,f;
}cow[maxN];

int cmp(Cow x,Cow y)
{
	return x.s>y.s;	
}

int main()
{
	int i,n,c,f;
	while(scanf("%d%d%d",&n,&c,&f)==3){
		n=(n-1)/2;
		for(i=1;i<=c;++i)
			scanf("%d%d",&cow[i].s,&cow[i].f);
		sort(cow+1,cow+1+c,cmp);
		while(!Q.empty()) Q.pop();
		int sum=0;
		for(i=1;i<=n;++i)
			Q.push(cow[i].f),sum+=cow[i].f;
		dpl
=sum;
		for(i=n+1;i<=c;++i)
			if(cow[i].f>=Q.top())
				dpl[i]=sum;
			else{
				sum=sum-Q.top()+cow[i].f;
				Q.pop();
				Q.push(cow[i].f);
				dpl[i]=sum;
			}	
		
		sum=0;
		while(!Q.empty()) Q.pop();
		for(i=c;i>=c-n+1;--i)
			Q.push(cow[i].f),sum+=cow[i].f;
		dpr[c-n+1]=sum;
		for(i=c-n;i>=1;--i)
			if(cow[i].f>=Q.top())
				dpr[i]=sum;
			else{
				sum=sum-Q.top()+cow[i].f;
				Q.pop();
				Q.push(cow[i].f);
				dpr[i]=sum;
			}
		bool ok=false;
		for(i=n+1;i<=c-n;++i)
			if(cow[i].f+dpl[i-1]+dpr[i+1]<=f){
				ok=true;
				printf("%d\n",cow[i].s);
				break;
			}
		if(!ok)
			printf("-1\n");	
	}
	return 0;
}