KCON help WA

Can anyone help me in understanding what’s wrong with my code.
I have tried various test cases manually and i am getting right answer, but in codechef
compiler most of the cases are coming W.A .
Question :https://www.codechef.com/LRNDSA06/problems/KCON

logic is standard (k-2)*sum of array + kadane for 2A , and all k values are handled as well ,
At the end i have done modulo

#include<iostream>
#include<math.h>
using namespace std;

int main()
{
    const unsigned int mx = 1000000007;
    long long int t;
    cin>>t;

    ///1 -2 1 1 -2 1
    while(t!=0)
    {
        long long int n,k;
        cin>>n>>k;
        long long int a[100000];
        long long int nsum = 0;

        for(long long int i=0;i<n;i++)
        {
            cin>>a[i];
            nsum = nsum + a[i];

        }
        if(k==1)
        {
            long long int sumi = 0;
            long long int maxi = 0;
            for(long long int i=0;i<n;i++)
            {
                sumi = sumi + a[i];
                if(sumi<0)
                    {
                        sumi = 0;
                    }
                if(sumi>maxi)
                {
                    maxi = sumi ;
                }
            }
             maxi = maxi % mx;

            cout<<maxi<<endl;
        }

        else
        {

        long long int maxi = 0;
        long long int x= 2;
        long long int sumi = 0;
        while(x!=0)
        {
            for(long long int i=0;i<n;i++)
            {
                sumi = sumi + a[i];
                if(sumi<0)
                    {
                        sumi = 0;
                    }
                if(sumi>maxi)
                {
                    maxi = sumi ;
                }
            }

            x--;
        }

        if(nsum>0)
        {
        nsum = nsum *(k-2);
        maxi = maxi + nsum ;
        }

        maxi = maxi % mx;

    cout<<maxi<<endl;
    }

        t--;

    }


}