二分

#include <bits/stdc++.h>
using namespace std;
const int N=1e5+6;
int n, m, a[N], l=0, r=0;
int main()
{
cin >> n >> m;
for (int i=1; i<=n; i++) {
cin >> a[i];
if (l<a[i]) l = a[i];
r += a[i];
}

while (l<=r) {
    int mid = l + (r-l)/2;
    
    int count = 1, tmp=0;  
    for (int i=1; i<=n; i++) {
        if (a[i]+tmp<=mid) tmp += a[i]; 
        else {
            count++;
            tmp = a[i];
        }
    }
    if (count<=m) r= mid-1;
    else l = mid+1;
}
cout<<l;
return 0;

}