This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
 
using namespace std;
#define pb push_back
#define all(x) x.begin(),x.end()
#define int long long
const int inf=1e9;
using i64=long long;
int n;
vector<int>a;
pair<i64 , int> test(const int lambda)
{
    pair<i64,int>sol={0,0};
    pair<i64,int> last={-1e18,0};
    for(int i=0;i<n;i++)
    {
        if(sol.first-lambda > last.first || (sol.first-lambda == last.first && sol.second<last.second))
        {
            last={sol.first+a[i]-lambda, sol.second+1};
        }
        else
        {
            last.first+=a[i];
        }
 
        if(sol.first<last.first || (sol.first==last.first && sol.second>last.second))
        {
            sol=last;
        }
    }
    return sol;
}
main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    int k;
    cin>>n>>k;
    a.resize(n);
    for(int i=0;i<n;i++)
    {
        cin>>a[i];
    }
    int st=0,dr=1e12;
    i64 rez=-1e18;
    while(st<=dr)
    {
        int m=(st+dr)/2;
        auto xd=test(m);
        if(xd.second <= k)
        {
            dr=m-1;
            rez=xd.first+1LL*k*m;
        }
        else
        {
            st=m+1;
        }
    }
    cout<<rez;
    return 0;
}
Compilation message (stderr)
feast.cpp:33:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   33 | main()
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