Merge sort

gistfile1.txt

void mergeArrays(int * arr, int l, int m, int r)
{
  // Compare element by element from arr[l:m]  with arr[m:r] and accordingly move index within idividual arr
  int lsize = m-l+1;  // this will include the middle element
  int rsize = r-m;
  int L[lsize];R[rsize];
  for(int i=0; i < lsize; i++)
    L[i] = arr[l+i];
  for(int i=0; i < rsize; i++)
    R[i] = arr[m+j];
    
  int i = 0;j = 0;index = l;
  while(i < lsize && j < rsize)
  {
    if (L[i] <= R [j])
    {
      arr[k] = L[i];
      i++;
    }
    else
    {
      arr[k] = R[j];
      j++;
    }
    k++;
  }
  while (i < lsize)
  {
    arr[k] = L[i];
    i++;k++;
  }
  while (j < rsize)
  {
    arr[k] = L[i];
    i++;k++;
  }
}

void mergeSort(int *arr, int l, int r)
{
// divide the arrays into left and right and then call merge on them to sort them
// Make sure that the l < r
  if (l < r)
  {
    m = (l+r)/2;
    mergeSort(arr, l, m);
    mergeSort(arr, m, r);
    mergeArrays(arr,l,m,r);
  }
}

int main()
{
  int arr[100] = {3,45,64,2,...};
  mergeSort(arr,0,100);
  return 0;
}