BZOJ 1029: [JSOI2007]建筑抢修 优先队列

//qscqesze
#include <cstdio>
#include <cmath>
#include <cstring>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <sstream>
#include <queue>
#include <typeinfo>
#include <fstream>
#include <map>
typedef long long ll;
using namespace std;
//freopen("D.in","r",stdin);
//freopen("D.out","w",stdout);
#define sspeed ios_base::sync_with_stdio(0);cin.tie(0)
#define maxn 200001
#define mod 10007
#define eps 1e-9
//const int inf=0x7fffffff;   //无限大
const int inf=0x3f3f3f3f;
/*

*/
//**************************************************************************************

inline ll read()
{
    int x=0,f=1;char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
    return x*f;
}

struct node
{
    int x,y;
};
bool cmp(node a,node b)
{
    return a.y<b.y;
}
node a[maxn];
priority_queue<int> q;
int main()
{
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
        a[i].x=read(),a[i].y=read();
    sort(a,a+n,cmp);
    int now=0;
    int ans=0;
    for(int i=0;i<n;i++)
    {
        if(now+a[i].x<=a[i].y)
        {
            ans++;
            now+=a[i].x;
            q.push(a[i].x);
        }
        else
        {
            int h=q.top();
            if(a[i].x<h)
            {
                q.pop();
                q.push(a[i].x);
                now=now+a[i].x-h;
            }
        }
    }
    cout<<ans<<endl;
}