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

void printArray(int A[], int size)
{
    int i;
    for (i=0; i < size; i++)
        printf("%d ", A[i]);

    printf("\n");

}

// Merges two subarrays of arr[].
// First subarray is arr[l..m]
// Second subarray is arr[m+1..r]

void merge(int arr[], int left, int middle, int right)
{
    int i1, j1, k1;
    int n1 = middle - left + 1;
    int n2 = right - middle ;

    /* create temp arrays */
    int L[n1], R[n2];

    /* Copy data to temp arrays L[] and R[] */

    for (i1 = 0; i1 < n1; i1++)
        L[i1] = arr[left + i1];

    for (j1 = 0; j1 < n2; j1++)
      {
		int index ;
		//index = left ;
		index =  middle + 1 + j1 ;
		//((middle+left  )+ j1) ;
		printf( "index:%d\n" , index  ) ;
        R[j1] = arr[ middle + 1 + j1  ] ;
	  }

    /* Merge the temp arrays back into arr[l..r]*/

    i1 = 0; // Initial index of first subarray
    j1 = 0; // Initial index of second subarray

    k1 = left; // Initial index of merged subarray

    while (i1 < n1 && j1 < n2)
    {
        if (L[i1] <= R[j1])
        {
            arr[k1] = L[i1];
            i1++;
        }
        else
        {
            arr[k1] = R[j1];
            printf( "else j1:%d k1:%d  right:%d\n" , j1, k1  ) ;
            j1++;
        }
        k1++;
    }

    /* Copy the remaining elements of L[], if there

    are any */

    while (i1 < n1)
    {
		printf( "n1 j1:%d i1:%d  right:%d\n" , j1, i1  ) ;
        arr[k1] = L[i1];
        i1++;
        k1++;
    }

    /* Copy the remaining elements of R[], if there
    are any */

    while (j1 < n2)
    {
		printf( "n2 j1:%d i1:%d  right:%d\n" , j1, i1  ) ;
        arr[k1] = R[j1];
        j1++;
        k1++;
    }
  printf( "left:%d middle:%d  right:%d\n" , left, middle, right ) ;
  printArray(arr, 4);
}

/* l is for left index and r is right index of the

sub-array of arr to be sorted */

void mergeSort(int arr[], int left, int right )
{

    if (left < right )
    {
        // Same as (l+r)/2, but avoids overflow for
        // large l and h
        int middle = (left+right)/2  ;
        // Sort first and second halves
        mergeSort(arr, left, middle);
        mergeSort(arr, middle+1, right);
        merge(arr, left, middle, right);
    }

}


int main()
{

    //int arr[] = {12, 11, 13, 5, 6, 7};
    int arr[] = { 12, 11, 13, 5 };
    int arr_size = sizeof(arr)/sizeof(arr[0]);
    printf("Given array is \n");
    printArray(arr, arr_size);
    mergeSort(arr, 0, arr_size - 1);
    printf("\nSorted array is \n");
    printArray(arr, arr_size);

    return 0;

}