[JSOI2007]建筑抢修 优先队列 贪心

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<queue>
using namespace std;
#define maxn 200000+4
#define ll long long
struct WORK{  int cost,ed ; }work[maxn];
bool cmp(WORK a,WORK b){ return a.ed<b.ed; }
priority_queue<ll>Q;
int main(){
    //freopen("input.in","r",stdin);
    int n,ans=0;
    ll total=0;
    scanf("%d",&n);
    for(int i=1;i<=n;++i) scanf("%d%d",&work[i].cost,&work[i].ed);
    sort(work+1,work+1+n,cmp);
    for(int i=1;i<=n;++i){
        if(total+work[i].cost<=work[i].ed) ++ans, Q.push(work[i].cost), total+=work[i].cost;
        else if(work[i].cost<Q.top()) total-=Q.top(),total+=work[i].cost,Q.pop(),Q.push(work[i].cost);
    }
    printf("%d",ans);
    return 0;
}