板材排版算法代码用C#编写，用遗传算法

以下是一个基于遗传算法的板材排版代码示例，使用C#编写。请注意，此示例仅用于演示目的，实际应用中需要根据具体情况进行修改和优化。

using System;
using System.Collections.Generic;
using System.Linq;

namespace BoardCuttingGA
{
    class Program
    {
        static void Main(string[] args)
        {
            Random random = new Random();
            int populationSize = 10;
            int maxGenerations = 100;
            double crossoverProbability = 0.6;
            double mutationProbability = 0.1;
            int boardWidth = 100;
            int boardHeight = 50;
            int[] pieces = { 30, 20, 15, 10, 5 };
            int pieceCount = pieces.Length;

            // Generate initial population
            List<Chromosome> population = new List<Chromosome>();
            for (int i = 0; i < populationSize; i++)
            {
                population.Add(new Chromosome(random, boardWidth, boardHeight, pieces));
            }

            // Evolution loop
            for (int generation = 0; generation < maxGenerations; generation++)
            {
                // Evaluate fitness of each chromosome
                foreach (Chromosome chromosome in population)
                {
                    chromosome.EvaluateFitness();
                }

                // Sort population by fitness
                population = population.OrderByDescending(c => c.Fitness).ToList();

                // Print best solution so far
                Console.WriteLine("Generation {0}: Best fitness = {1}", generation, population[0].Fitness);
                Console.WriteLine(population[0]);

                // Create new population
                List<Chromosome> newPopulation = new List<Chromosome>();

                // Elitism: add best chromosome to new population
                newPopulation.Add(population[0]);

                // Crossover
                while (newPopulation.Count < populationSize)
                {
                    Chromosome parent1 = SelectParent(population, random);
                    Chromosome parent2 = SelectParent(population, random);

                    if (random.NextDouble() < crossoverProbability)
                    {
                        Chromosome child1, child2;
                        Crossover(parent1, parent2, out child1, out child2);
                        newPopulation.Add(child1);
                        newPopulation.Add(child2);
                    }
                    else
                    {
                        newPopulation.Add(parent1);
                        newPopulation.Add(parent2);
                    }
                }

                // Mutation
                foreach (Chromosome chromosome in newPopulation)
                {
                    if (random.NextDouble() < mutationProbability)
                    {
                        chromosome.Mutate();
                    }
                }

                // Replace old population with new population
                population = newPopulation;
            }
        }

        static Chromosome SelectParent(List<Chromosome> population, Random random)
        {
            double totalFitness = population.Sum(c => c.Fitness);
            double selectionValue = random.NextDouble() * totalFitness;

            foreach (Chromosome chromosome in population)
            {
                selectionValue -= chromosome.Fitness;
                if (selectionValue < 0)
                {
                    return chromosome;
                }
            }

            return population[population.Count - 1];
        }

        static void Crossover(Chromosome parent1, Chromosome parent2, out Chromosome child1, out Chromosome child2)
        {
            child1 = new Chromosome(parent1);
            child2 = new Chromosome(parent2);

            int cutPoint = parent1.Random.Next(0, parent1.PieceCount);

            for (int i = cutPoint; i < parent1.PieceCount; i++)
            {
                child1.Pieces[i] = parent2.Pieces[i];
                child2.Pieces[i] = parent1.Pieces[i];
            }
        }
    }

    class Chromosome
    {
        public int[] Pieces { get; private set; }
        public int PieceCount { get; private set; }
        public double Fitness { get; private set; }
        public Random Random { get; private set; }
        public int BoardWidth { get; private set; }
        public int BoardHeight { get; private set; }

        public Chromosome(Random random, int boardWidth, int boardHeight, int[] pieces)
        {
            Random = random;
            BoardWidth = boardWidth;
            BoardHeight = boardHeight;
            Pieces = pieces;
            PieceCount = pieces.Length;
        }

        public Chromosome(Chromosome other)
        {
            Random = other.Random;
            BoardWidth = other.BoardWidth;
            BoardHeight = other.BoardHeight;
            Pieces = new int[other.PieceCount];
            Array.Copy(other.Pieces, Pieces, PieceCount);
        }

        public void EvaluateFitness()
        {
            int[,] board = new int[BoardWidth, BoardHeight];

            // Try to place each piece on the board
            for (int i = 0; i < PieceCount; i++)
            {
                if (!PlacePiece(board, Pieces[i]))
                {
                    // If a piece can't be placed, set fitness to zero and return
                    Fitness = 0;
                    return;
                }
            }

            // Calculate fitness as the total area of all placed pieces
            int totalArea = 0;
            for (int x = 0; x < BoardWidth; x++)
            {
                for (int y = 0; y < BoardHeight; y++)
                {
                    if (board[x, y] > 0)
                    {
                        totalArea += Pieces[board[x, y] - 1];
                    }
                }
            }

            Fitness = totalArea;
        }

        private bool PlacePiece(int[,] board, int piece)
        {
            // Try to place piece in every possible position
            for (int x = 0; x <= BoardWidth - piece; x++)
            {
                for (int y = 0; y <= BoardHeight - piece; y++)
                {
                    if (IsFree(board, x, y, piece))
                    {
                        // Place piece on board
                        for (int i = x; i < x + piece; i++)
                        {
                            for (int j = y; j < y + piece; j++)
                            {
                                board[i, j] = piece;
                            }
                        }
                        return true;
                    }
                }
            }

            // Piece can't be placed on board
            return false;
        }

        private bool IsFree(int[,] board, int x, int y, int piece)
        {
            for (int i = x; i < x + piece; i++)
            {
                for (int j = y; j < y + piece; j++)
                {
                    if (board[i, j] > 0)
                    {
                        return false;
                    }
                }
            }

            return true;
        }

        public void Mutate()
        {
            // Swap two random pieces
            int index1 = Random.Next(0, PieceCount);
            int index2 = Random.Next(0, PieceCount);
            int temp = Pieces[index1];
            Pieces[index1] = Pieces[index2];
            Pieces[index2] = temp;
        }

        public override string ToString()
        {
            return string.Join(", ", Pieces);
        }
    }
}