2802: [Poi2012]Warehouse Store 贪心 priority_queue

贪心。每次尽量往里放，否则踢出之前$b[i]$最大的放进当前的。

#include<iostream>
#include<cstdio>
#include<queue>
#include<vector>
#define N 250005
#define ll long long
#define pa pair<int,int>
using namespace std;
int a[N],b[N];
int n,ans;
ll sum;
bool vis[N];
priority_queue<pa,vector<pa> > q;
inline int read()
{
    int a=0,f=1; char c=getchar();
    while (c<'0'||c>'9') {if (c=='-') f=-1; c=getchar();}
    while (c>='0'&&c<='9') {a=a*10+c-'0'; c=getchar();}
    return a*f;
}
int main()
{
    n=read(); 
    for (int i=1;i<=n;i++) a[i]=read();
    for (int i=1;i<=n;i++) b[i]=read();
    for (int i=1;i<=n;i++)
    {
        sum+=a[i];
        if (sum>=b[i])
        {
            ans++;
            sum-=b[i];
            q.push(make_pair(b[i],i));
        }
        else if (!q.empty()&&q.top().first>b[i])
        {
            sum+=q.top().first-b[i];
            q.pop();
            q.push(make_pair(b[i],i));
        }
    }
    while (!q.empty())
        vis[q.top().second]=1,q.pop();
    cout << ans << endl;
    for (int i=1;i<=n;i++)
        if (vis[i]) printf("%d ",i);
    return 0;
}