n-queens/src/chess.cpp

#include "chess.hpp"
#include <iostream>
#include <random>

std::default_random_engine generator;

void InitializeGenerator(void) {
    generator.seed(std::random_device{}());
}

int GenerateRandomNumber(int generationLimit) {
    int generatedNumber;
    std::uniform_int_distribution<> distribution(0, generationLimit - 1);
    generatedNumber = distribution(generator);
    return generatedNumber;
}

GeneticDefaults::GeneticDefaults(void) {
    size = 8;
    length = 8;
}

GeneticDefaults::GeneticDefaults(unsigned int size, unsigned int length) {
    this->size = size;
    this->length = length;
}

GeneticChess::GeneticChess(void) {
    generationCount = 0;
    InitializeGenerator();
    // population init part of vector resize
    board.resize(genetics.size, 0);
    for (int i = 0; i < board.size(); ++i) { 
        board.at(i) = GenerateRandomNumber(genetics.size);
    }
}


void GeneticChess::Print(void) {
    std::cout << generationCount << ':' << std::endl;
    for (int i : board) {
        std::cout << '[';
        for (int j = 0; j < genetics.size; ++j) {
            if (j == i) { std::cout << "Q"; }
            else { std::cout << ' '; }
        }
        std::cout << ']';
        std::cout << std::endl;
    }
}

// Gets the fitness of the population
unsigned int GeneticChess::GetFitness(void) {
    int fitness = 0;
    for (int i : board) { 
        if (!IsQueenThreatened(i)) { fitness++; }
    }
    return fitness;
}

//
void GeneticChess::Selection(void) {

}

// Crossover on the population
void GeneticChess::Crossover(void) {

}

// Mutates the population
void GeneticChess::Mutation(void) {

}

// Checks if the passed in queen is threatened on the board
// Impossible for queens to be threatened by same row
bool GeneticChess::IsQueenThreatened(const unsigned int queenRow) {
    int queenCol = board.at(queenRow);
    int diffRow, diffCol;
    for (int i = 0; i < genetics.size; ++i) {
        if (i == queenRow) { continue; }
        diffCol = queenCol - board.at(i);
        diffRow = queenRow - i;
        if (diffCol == 0) { return true; } // Column threat
        if (diffCol == diffRow) { return true; }
    }
    return false;
}