思路：二分答案经典题吧。。。。注意边界就OK了

//By SiriusRen

#include <cstdio>

#include <algorithm>

using namespace std;

int n,m,a[100050],ans;

bool check(int x){

    int jy=0,temp=0;

    for(int i=1;i<=n;i++){

        if(a[i]+jy>x){

            jy=0;

            temp++;

            if(temp>m)return 0;

        }

        jy+=a[i];

        if(temp>=m||jy>x)return 0;

    }

    return 1;

}

int main(){

    scanf("%d%d",&n,&m);

    for(int i=1;i<=n;i++)scanf("%d",&a[i]);

    int Left=0,Right=0x3fffffff;

    while(Left<=Right){

        int Mid=(Left+Right)>>1;

        if(check(Mid))Right=Mid-1,ans=Mid;

        else Left=Mid+1;

    }

    printf("%d\n",ans);

}