题解 | 牛牛与切割机

#include <climits>
#include <iostream>
#include <vector>
using namespace std;

int main()
{
    int n;
    cin>>n;

    vector<long long> a(n+1,0);

    long long sum=0;

    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
        sum+=a[i];
    }

    long long sumleft=0;
    long long mincost=LLONG_MAX;

    for(int i=1;i<n;i++)
    {
        sumleft+=a[i];
        long long sumright=sum-sumleft;
        long long cost=sumright*sumleft;
        if(cost<mincost) mincost=cost;
    }

    cout<<mincost<<endl;
    return 0;
}