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

#include <sys/time.h>
struct timeval start_time, stop_time;
int    elapsed;

#define SWAP(A,B) {int temp=A;A=B;B=temp;}
void printArray(int a[], int n) ;


// A function to sort the algorithm using Odd Even sort 
void oddEvenSort(int a[], int n) 
{ 
    int  isSorted = 0; // Initially array is unsorted 
    int  i;
  
    while (!isSorted) 
    { 
       isSorted = 1;	// Assume the array is sorted...
  
        // Even phase
        for (i = 0; i < n-1; i = i + 2) 
        { 
           if (a[i] > a[i+1]) 
           { 
	      SWAP(a[i], a[i+1]);
              isSorted = 0; 	// Detects that array was not sorted
           } 
        } 

	if ( n < 1000 )
        {
	   printf(" Even: ");
	   printArray(a, n);
        }

        // Odd phase
        for (i = 1; i < n-1; i = i + 2) 
        { 
           if (a[i] > a[i+1]) 
           { 
	      SWAP(a[i], a[i+1]);
              isSorted = 0; 	// Detects that array was not sorted
           } 
        } 

	if ( n < 1000 )
        {
	   printf("  Odd: ");
	   printArray(a, n);
	   printf("\n");
        }
    } 
  
    return; 
} 

// A utility function ot print an array of size n 
void printArray(int a[], int n) 
{ 
   for (int i=0; i < n; i++) 
       printf("%d ", a[i]);
   printf("\n"); 
} 

// Driver program to test above functions. 
int main (int argc, char *argv[])
{ 
   int *arr;
   int n;
   int i;
  
   if (argc < 2)
   {
      printf("Usage error: %s N (N=# elements in array to sort)\n", argv[0]);
      exit(1);
   }

   n = atoi( argv[1] );

   arr = calloc(n, sizeof(int));

   for ( i = 0 ; i < n; i++ )
      arr[i] = rand()%1000;

   if ( n < 1000 )
   {  printf("       ");
      printArray(arr, n); 
   }

   gettimeofday(&start_time, NULL);   // Record current sys time as start_time

   oddEvenSort(arr, n); 

   gettimeofday(&stop_time, NULL);   // Record current sys time as stop_time

   elapsed = (stop_time.tv_sec*1000000 + stop_time.tv_usec) -
                (start_time.tv_sec*1000000 + start_time.tv_usec);
   printf("Elasped time = %d micro secs\n", elapsed);


   if ( n < 1000 )
   {  printf("       ");
      printArray(arr, n); 
   }

   // Check if array is sorted...
   int min = arr[0];
   for ( i = 1; i < n; i++ )
   {
      if ( arr[i] < min )
      {
         printf("Sort error detected: %d %d !!!\n", min, arr[i]);
         exit(1);
      }

      min = arr[i];
   }

  
   return (0); 
}