Dear all,
I've written the heapsort algorithm as it's implemented in GSL
You can find it in attachment...
but I'm not able to get it working...I don't understand where I'm wrong and
this is getting me crazy :-(
...It would be highly appreciated if anyone could help me
thanks in advance
--frank
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
static void index_downheap(unsigned int *, const double *, const unsigned int, unsigned int);
void double_sort_index(unsigned int *, const double *, const unsigned int);
void double_sort_index(unsigned int *p, const double *list, const unsigned int n)
{
unsigned int N;
unsigned int i, k;
if ( n == 0 )
return;
for ( i = 0 ; i < n ; i++ )
p[i] = i;
N = n - 1;
k = N / 2;
k++;
do
{
k--;
index_downheap( p, list, N, k );
}
while ( k > 0 );
while ( N > 0 )
{
unsigned int tmp = p[0];
p[0] = p[N];
p[N] = tmp;
index_downheap( p, list, --N, 0 );
}
}
static void index_downheap(unsigned int *p, const double *list, const unsigned int N, unsigned int k)
{
const unsigned int pki = p[k];
while ( k <= N / 2 )
{
unsigned int j = 2 * k;
if ( (j < N) && (list[p[j]] < list[p[j]+1]) )
{
j++;
}
if ( !(list[pki] < list[p[j]]) )
{
break;
}
p[k] = p[j];
k = j;
}
p[k] = pki;
}
int main(int argc, char *argv[])
{
int i;
unsigned int *perm;
double *x;
x = (double *) malloc( 5 * sizeof(double) );
x[0]=10.0;
x[1]=9.0;
x[2]=8.0;
x[3]=7.0;
x[4]=6.0;
for( i=0; i < 5; i++ )
printf("%f\n", x[i]);
perm = (unsigned int *) malloc ( 5 * sizeof(unsigned int) );
double_sort_index(perm, x, 5);
printf("\n--SORTED?--\n");
for( i=0; i < 5; i++ )
printf("%f\n", x[perm[i]]);
exit(0);
}
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