/*------------------------------------------------------------------------** geqo_px.c**	 position crossover [PX] routines;*	 PX operator according to Syswerda*	 (The Genetic Algorithms Handbook, L Davis, ed)** $PostgreSQL: pgsql/src/backend/optimizer/geqo/geqo_px.c,v 1.10 2003/11/29 22:39:49 pgsql Exp $**-------------------------------------------------------------------------*//* contributed by:   =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=   *  Martin Utesch				 * Institute of Automatic Control	   *   =							 = University of Mining and Technology =   *  utesch@aut.tu-freiberg.de  * Freiberg, Germany				   *   =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*= *//* the px algorithm is adopted from Genitor : *//*************************************************************//*															 *//*	Copyright (c) 1990										 *//*	Darrell L. Whitley										 *//*	Computer Science Department								 *//*	Colorado State University								 *//*															 *//*	Permission is hereby granted to copy all or any part of  *//*	this program for free distribution.   The author's name  *//*	and this copyright notice must be included in any copy.  *//*															 *//*************************************************************/#include "postgres.h"#include "optimizer/geqo_random.h"#include "optimizer/geqo_recombination.h"/* px * *	 position crossover */voidpx(Gene *tour1, Gene *tour2, Gene *offspring, int num_gene, City *city_table){	int			num_positions;	int			i,				pos,				tour2_index,				offspring_index;	/* initialize city table */	for (i = 1; i <= num_gene; i++)		city_table[i].used = 0;	/* choose random positions that will be inherited directly from parent */	num_positions = geqo_randint(2 * num_gene / 3, num_gene / 3);	/* choose random position */	for (i = 0; i < num_positions; i++)	{		pos = geqo_randint(num_gene - 1, 0);		offspring[pos] = tour1[pos];	/* transfer cities to child */		city_table[(int) tour1[pos]].used = 1;	/* mark city used */	}	tour2_index = 0;	offspring_index = 0;	/* px main part */	while (offspring_index < num_gene)	{		/* next position in offspring filled */		if (!city_table[(int) tour1[offspring_index]].used)		{			/* next city in tour1 not used */			if (!city_table[(int) tour2[tour2_index]].used)			{				/* inherit from tour1 */				offspring[offspring_index] = tour2[tour2_index];				tour2_index++;				offspring_index++;			}			else			{					/* next city in tour2 has been used */				tour2_index++;			}		}		else		{						/* next position in offspring is filled */			offspring_index++;		}	}}