XEPTRUNG C++

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int n,m,a[100001];
long long s=0,res;
void nhap()
{
    cin>>n>>m;
    for (int i=1;i<=n;i++)
        cin>>a[i];
}

bool check(ll x)
{
   ll d=1,s=0;
   for(int i=1;i<=n;i++)
   {
        if(s+a[i]<=x) s=s+a[i];
        else
            if(a[i]>x) return false;
            else
            {
                d++;
                if(d>m) return false;
                s=a[i];
            }
   }
   //cout<<d;
   return true;
}

ll tknp(ll l,ll r)
{
    ll k=0,mid;
    while(l<=r)
    {
        mid=(l+r)/2;
        if(check(mid)==true)
        {
            k=mid;
            r=mid-1;
        }
        else
            l=mid+1;
    }
    return k;
}

/*long long tknp(long long l,long long r)
{
    if (l>r) return;
    long long mid=(l+r)/2;
    if (check(mid)==true)
    {
        res=mid;
        find(l,mid-1);
    }
    else find(mid+1,r);
}*/

void giai()
{
    ll dmax=0,s=0;
    for(int i=1;i<=n;i++)
    {
        s=s+a[i];
        if(a[i]>dmax) dmax=a[i];
    }
    ll k=tknp(1,s);
    cout<<k;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    freopen("xeptrung.inp","r",stdin);
    freopen("xeptrung.out","w",stdout);
    nhap();
    giai();
}