programming-examples/c/Search_Sorting/C Program to Implement Bitonic sort.c

/*
 *  C Program to Implement Bitonic sort
 */
#include <stdio.h>
#include <stdlib.h>
#define MAX 8
#define SWAP(x,y) t = x; x = y; y = t;

void compare();
void bitonicmerge(int, int, int);
void recbitonic(int, int, int);
void sort();

int data[MAX];
int up = 1;
int down = 0;

int main()
{
    int i;
    printf("\nEnter the data");
    for (i = 0; i < MAX ; i++)
        {
            scanf("%d", &data[i]);
        }
    sort();
    for (i = 0; i < MAX; i++)
        {
            printf("%d ", data[i]);
        }
}
/*
 * compare and swap based on dir
 */
void compare(int i, int j, int dir)
{
    int t;
    if (dir == (data[i] > data[j]))
        {
            SWAP(data[i], data[j]);
        }
}
/*
 * Sorts a bitonic sequence in ascending order if dir=1
 * otherwise in descending order
 */
void bitonicmerge(int low, int c, int dir)
{
    int k, i;
    if (c > 1)
        {
            k = c / 2;
            for (i = low; i < low+k ; i++)
                compare(i, i+k, dir);
            bitonicmerge(low, k, dir);
            bitonicmerge(low+k, k, dir);
        }
}
/*
 * Generates bitonic sequence by sorting recursively
 * two halves of the array in opposite sorting orders
 * bitonicmerge will merge the resultant data
 */
void recbitonic(int low, int c, int dir)
{
    int k;
    if (c > 1)
        {
            k = c / 2;
            recbitonic(low, k, up);
            recbitonic(low + k, k, down);
            bitonicmerge(low, c, dir);
        }
}

/*
 * Sorts the entire array
 */
void sort()
{
    recbitonic(0, MAX, up);
}
/*
*OUTPUT:
/*Average case

Enter the data
3 5 8 9 7 4 2 1
1  2  3  4  5  7  8  9
$  a.out
/*Worst case
Enter the data
100 99 98 97 96 95 94 93
93  94  95  96  97  98  99  100
/*Best case
Enter the data
1111 2222 3333 4444 5555 6666 7777 8888
1111  2222  3333  4444  5555  6666  7777  8888
*/