80分 WA#4求调

#include<bits/stdc++.h>
using namespace std;
int sum[100005],n,m,a[100005];
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		sum[i]=sum[i-1]+a[i];
		//cout<<sum[i]<<" ";
	}
	int l=1,r=1e9;
	while(l<r){
		int mid=(l+r)/2;
		int last=0,ans=1;
		for(int i=1;i<=n;i++){
			if(sum[i]-sum[last]>mid){
				ans++;
				last=i-1;
			}
		}
		if(ans>m){
			l=mid+1;
		}else{
			r=mid;
		}
	}
	cout<<r;
	return 0;
}