#include <stdio.h>

//Calculate array size
#define ARRAY_SIZE(a)  sizeof(a)/sizeof(a[0])


//swap function not handle null pointer scenario
//not much safe to use
void swap(int *s1, int *s2)
{
    int temp = *s1;
    *s1 = *s2;
    *s2 = temp;
}


// Function to move all zeros present in the array to the end
void moveAllZeroesAtArrayEnd(int arr[], int n)
{
    int i =0,j = 0;
    // each time we encounter a non-zero, j is incremented and
    // the element is placed before the pivot
    for (i = 0; i < n; i++)
    {
        if (arr[i] != 0)//non-zero
        {
            swap(&arr[i],&arr[j]);
            j++;
        }
    }
}

// function to rearrange the array elements
// after modification
int arrayModification(int arr[], int n)
{
    int i =0;

    const int status  = (n>1)? 0: -1;

    // traverse the array
    for (i = 0; i < n - 1; i++)
    {
        // if current element valid and equal to next
        if ((arr[i] != 0) && (arr[i] == arr[i + 1]))
        {
            // double current index value
            arr[i] = 2 * arr[i];

            // put 0 in the next index
            arr[i + 1] = 0;
            // increment by 1 so as to move two
            // indexes ahead during loop iteration
            i++;
        }
    }
    //call function when input array is valid
    if(status ==0)
    {
        //move all the zeros at the end of the array
        moveAllZeroesAtArrayEnd(arr, n);
    }

    return status;
}


int main()
{
    int arr[] = { 0, 2, 2, 2, 0, 6, 6, 0, 0, 8 };
    int i = 0;

    //get array size
    int arr_size = ARRAY_SIZE(arr);

    //modify and rearrange the array
    const int status = arrayModification(arr, arr_size);

    if(status == 0)
    {
        //print array element
        for (i = 0; i < arr_size; i++)
        {
            printf("%d ",arr[i]);
        }
    }
    else
    {
        printf("Enter valid array !");
    }
    
    return 0;
}