bai3truong.cpp

#include<iostream>
#include<vector>
#include<algorithm>

#define long long long
#define nln '\n'

using namespace std;

bool check(vector<long> a, long k, long m)
{
    long cnt = 1, s = 0;
    for (auto i : a){
        if (s+i <= m)
            s +=i;
        else{
            cnt++;
            s = i;
        }
        if (cnt > k)
            return 0;
    }
    return 1;
}

int main()
{
    cin.tie(0)->sync_with_stdio(0);
    freopen("bai3truong.inp", "r", stdin);
    long n, k;
    cin >> n >> k;
    vector<long> a(n);
    long rig = 0;
    for (auto &i : a){
        cin >> i;
        rig += i;
    }

    long lef = *max_element(a.begin(), a.end()), res = -1;
    while (lef <= rig){
        long mid = (lef+rig)/2;
        if (check(a, k, mid))
            res = mid, rig = mid-1;
        else
            lef = mid+1;
    }

    cout << res << nln;

    return 0;
}