quicksort.c

/* Quick Sort */


#include <stdio.h>
void quicksort (int a[], int low, int high);
int partition(int a[], int low, int high);
int a[5] = {55, 1, 78, 13, 45};
void main( )
{
int i, n;
printf("\nOriginal array");
for(i=0; i < 5; i++)
printf("%4d", a[i]);
quicksort(a, 0, 4);
printf("\nThe sorted array is \n");
for(i=0; i < 5; i++)
printf("%4d", a[i]);
}
void quicksort (int a[], int low, int high)
{
int j;
if (low < high)
{
j = partition(a,low, high);
quicksort (a, low, j-1);
quicksort(a, j+1, high);
}
}
int partition(int a[], int low, int high)
{
int i, j, temp, key;
key = a[low];
i = low + 1;
j = high;
while (1)
{
while (i < high && key >= a[i])
i++;
while (key < a[j])
j--;
if (i < j)
{
temp = a[i];
a[i] = a[j];
a[j] = temp;
}
else
{
temp = a[low];
a[low] = a[j];
a[j] = temp;
}
return j;
}
}