shuffle.c File Reference

Random shuffle and related functions. More...

#include "libtpcmodel.h"

Go to the source code of this file.

Functions
void	random_shuffle (int *array, int n)
void	randperm (int *array, int n, int a)

Detailed Description

Random shuffle and related functions.

Author

Vesa Oikonen

Definition in file shuffle.c.

Function Documentation

random_shuffle()

void random_shuffle	(	int *	array,
		int	n )

Random shuffle: arrange the n elements of array in random order. Only effective if N is much smaller than RAND_MAX.

Definition at line 13 of file shuffle.c.

{
  if(n<=1 || array==NULL) return;
  int i, j, tmp;
  for(i=0; i<n-1; i++) {
    j=i+rand()/(RAND_MAX/(n-i)+1);
    tmp=array[j]; array[j]=array[i]; array[i]=tmp;
  }
}

Referenced by randperm().

randperm()

void randperm	(	int *	array,
		int	n,
		int	a )

Random permutation: given (allocated) array of length n is filled with random permutation of numbers in the range [a:n+a-1]; that is, each number once in random order.

Definition at line 29 of file shuffle.c.

{
  if(n<1 || array==NULL) return;
  int i;
  for(i=0; i<n; i++) array[i]=i+a;
  random_shuffle(array, n);
}