Valera and Fruits CodeForces - 441B

原题链接

考察:贪心+模拟

思路:

        枚举从开始时间到结束时间每一天的收益.设收益为w,每天最多取min(树的苹果,v-w)个.注意不是最多取v个.因为是按天数枚举的.考虑存在苹果树没有取完隔天再取的情况,所以用了优先队列.

#include <iostream>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
const int N = 3005;
typedef pair<int,int> PII;
int n,v;
PII p[N];
struct cmp{
    bool operator()(PII x,PII y){
        if(x.first==y.first) return x.second<y.second;
        return x.first>y.first;
    }
};
priority_queue<PII,vector<PII>,cmp> q;
int solve()
{
    int st = p[n].first,ed = p[1].first,res =0;
    for(int i=st;i<=ed+1;i++)
    {
        int w = 0;
        while(q.size()&&q.top().first<=i)
        {
            PII u = q.top(); q.pop();
            if(u.first+1<i) continue;
            int val =min(u.second,v-w);
            w+=val; u.second-=val;
            if(u.second) q.push(u);
            if(w==v) break;
        }
        res+=w;
    }
    return res;
}
int main()
{
    scanf("%d%d",&n,&v);
    for(int i=1;i<=n;i++)
      scanf("%d%d",&p[i].first,&p[i].second),q.push(p[i]);
    sort(p+1,p+n+1,cmp());
    int res = solve();
    printf("%d\n",res);
    return 0;
}