Find subarray containing atleast k numbers with maximum sum

subarray-atleast-k-numbers.cpp

#include "bits/stdc++.h"

using namespace std;
int main()
{
	int n,i,k;
	cin>>n;
	vector<int> v;
	for(i=0;i<n;i++)
	{
		int x;
		cin>>x;
		v.push_back(x);
	}
	cin>>k;

	int maxSum[n];
	maxSum[0] = v[0];

	int max_here = v[0];
	for(i=1;i<n;i++)
	{
		max_here = max(v[i],max_here+v[i]);
		maxSum[i] = max_here;
	}
	int sum=0;
	if(k>n)
	{
		cout<<"Not possible"<<endl;
	}
	else
	{
		if(k>0)
		{
			for(i=0;i<k;i++)
			{
				sum+=v[i];
			}
			int max_sum = sum;
			for(i=k;i<n;i++)
			{
				sum+=v[i]-v[i-k];
				
				max_sum = max(max_sum, sum);

				max_sum = max(max_sum,sum+maxSum[i-k]);
			}
			cout<<max_sum<<endl;	
		}
		else if(k<=0)
		{
			int max_sum=INT_MIN;
			for(i=0;i<n;i++)
			{
				if(max_sum<maxSum[i])
				{
					max_sum = maxSum[i];
				}
			}
			if(max_sum<0)
			{
				max_sum=0;
			}
			cout<<max_sum<<endl;
		}
	}
	
}