Aggresive Cows Samsung

#include <iostream>
using namespace std;

void merge(int a[], int l, int mid, int r){
    int n1= mid -l +1;
    int n2= r-mid;

    int b[n1], c[n2];
    for(int i=0; i<n1; i++) b[i]=a[i+l];
    for(int j=0; j<n2; j++) c[j]=a[mid +j +1];

    int i=0, j=0, k=l;
    while(i<n1 && j<n2){
        if(b[i]<=c[j]) a[k++]=b[i++];
        else a[k++]=c[j++];
    }

    while(i<n1) a[k++]=b[i++];
    while(j<n2) a[k++]=c[j++];
}


void mergeSort(int a[],int l, int r){
    if(l<r){
        int mid =(l + r)/2;
        //calling recursive frunctions for two subarrays
        mergeSort(a, l,mid);
        mergeSort(a,mid+1,r);

        //merging arrays
        merge(a,l,mid,r);
    }
}

bool isPossible(int a[], int n, int cows, int mid){
    int curPos=a[0];
    int filled=1;

    for(int i=1; i<n; i++){
        if(curPos+ mid <=a[i]){
            curPos=a[i];
            filled++;
            if(filled==cows) return true;
        }
    }
    return false;
}

int findMinDist(int a[], int n, int cows){
    int low=a[0], high=a[n-1];

    int res=0;
    while(low< high){
        int mid=(low + high)/2;

        if(isPossible(a,n, cows, mid)){
            res=max(res,mid);
            low=mid +1;
        }else high = mid;
    }
    return res;
}

int main() {
    int t;
    cin>>t;
    while(t--){
        int n,cows;
        cin>>n>>cows;

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

        mergeSort(a,0,n-1);

        int ans=findMinDist(a,n, cows);
        cout<<ans<<endl;
    }
}