80分 但不是T4 是T5

#include<bits/stdc++.h>
using namespace std;
long long a[1000010],n,m,sum,tr,l;
long long minn;
bool etr(int yiban){
	 int ans=0,mt=1;
	 for(int i=1;i<=n;i++){
	 	if(ans+a[i]<=yiban) ans+=a[i];
	 	else{
	 		ans=a[i];
	 		mt++;
		 }
	 }
	 if(mt<=m){
	 	return 1;
	 }else{
	 	return 0;
	 }
}
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		sum+=a[i];
		l=max(l,a[i]);
	}
	long long r=sum;
	while(l<=r){
		minn=(l+r)/2;
		if(etr(minn)==1){
			tr=minn;
			r=minn-1;
		}else{
		    l=minn+1;
		}
	}
	cout<<tr;
}