/* ----------------------------------------------------------------------------  ex12.C  mbwall 13apr95  Copyright (c) 1995-1996  Massachusetts Institute of Technology DESCRIPTION:   This example shows how to use an order-based string genome.---------------------------------------------------------------------------- */#include <stdio.h>#include <stdlib.h>#include <iostream.h>#include <fstream.h>#include <ga/ga.h>#include <ga/GAStringGenome.h>#include <ga/GAStringGenome.C>// This is the declaration of the objective function that we will use in this// example.float objective(GAGenome &);// Every genome must have an initializer.  Here we declare our own initializer// that will be used in this example.void AlphabetInitializer(GAGenome &);intmain(int argc, char *argv[]){  cout << "Example 12\n\n";  cout << "This program illustrates the use of order-based strings.  The\n";  cout << "string in this problem contains 26 letters, a to z.  It tries\n";  cout << "to put them in alphabetic order.\n\n";  cout.flush();// See if we've been given a seed to use (for testing purposes).  When you// specify a random seed, the evolution will be exactly the same each time// you use that seed number.  for(int ii=1; ii<argc; ii++) {    if(strcmp(argv[ii++],"seed") == 0) {      GARandomSeed((unsigned int)atoi(argv[ii]));    }  }// Set the default values of the parameters then parse for command line changes  int i;  GAParameterList params;  GASteadyStateGA::registerDefaultParameters(params);  params.set(gaNpopulationSize, 25);	// population size  params.set(gaNpCrossover, 0.9);	// probability of crossover   params.set(gaNpMutation, 0.01);	// probability of mutation  params.set(gaNnGenerations, 4000);	// number of generations  params.parse(argc, argv, gaFalse);// Now create the GA and run it.  We first create a genome with the// operators we want.  Since we're using a template genome, we must assign// all three operators.  We use the order-based crossover site when we assign// the crossover operator.  GAStringAlleleSet alleles;  for(i=0; i<26; i++)    alleles.add('a'+i);  GAStringGenome genome(26, alleles, objective);  genome.initializer(AlphabetInitializer);  genome.mutator(GAStringSwapMutator);  GASteadyStateGA ga(genome);  ga.parameters(params);  ga.crossover(GAStringPartialMatchCrossover);  ga.evolve();  genome = ga.statistics().bestIndividual();  cout << "the ga generated the following string (objective score is ";  cout << genome.score() << "):\n" << genome << "\n";  cout << genome.className() << "\n";  return 0;} /* ----------------------------------------------------------------------------Objective function  The objective function gives one point for every number in the correctposition.  We're trying to get a sequence of numbers from n to 0 in descendingorder.---------------------------------------------------------------------------- */floatobjective(GAGenome & c){  GAStringGenome & genome = (GAStringGenome &)c;  float score = 0;  for(unsigned int i=0; i<genome.size(); i++)    score += (genome.gene(i) == 'a' + i);  return score;}/* ----------------------------------------------------------------------------AlphabetInitializer  This initializer creates a string genome with the letters a-z as its elements.  Once we have assigned all the values, we randomize the string.---------------------------------------------------------------------------- */voidAlphabetInitializer(GAGenome & c){  GAStringGenome &genome=(GAStringGenome &)c;  unsigned int i;  for(i=0; i<genome.size(); i++)    genome.gene(25-i, 'a'+i);  for(i=0; i<genome.size(); i++)    if(GARandomBit()) genome.swap(i, GARandomInt(0, genome.size()-1));}