Inversion count

#include <stdio.h>
#include <stdlib.h>

long long merge(long long arr[], long long temp[], long long left, long long mid, long long right)
{
  long long i, j, k;
  long long inv_count = 0;

  i = left;
  j = mid;
  k = left;
  while ((i <= mid - 1) && (j <= right))
  {
    if (arr[i] <= arr[j])
    {
      temp[k++] = arr[i++];
    }
    else
    {
      temp[k++] = arr[j++];


      inv_count = inv_count + (mid - i);
    }
  }


  while (i <= mid - 1)
    temp[k++] = arr[i++];


  while (j <= right)
    temp[k++] = arr[j++];


  for (i=left; i <= right; i++)
    arr[i] = temp[i];

  return inv_count;
}

long long mergeSort(long long arr[], long long temp[], long long left,long long right)
{
  long long mid, inv_count = 0;
  if (right > left)
  {

    mid = (right + left)/2;


    inv_count  = mergeSort(arr, temp, left, mid);
    inv_count += mergeSort(arr, temp, mid+1, right);


    inv_count += merge(arr, temp, left, mid+1, right);
  }
  return inv_count;
}



  int main()
{
	int t;
	scanf("%d",&t);
	long n;
	while(t--)
	{
		scanf("%ld",&n);
		long long a[n],temp[n],i,j;
		for(i=0;i<n;i++){
			scanf("%lld",&a[i]);
			temp[i]=0;
		}
		long long count=mergeSort(a,temp,0,n-1);

		printf("%lld\n",count);
	}
	return 0;
}