C# Homework Help - 8 queens problem

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C# Homework Question ; C# Logical Puzzles, Games, and Algorithms: 8 queens problem

 

C# Homework Solution: 

using System;

class EightQueensProblem
{
    static int boardSize = 8;
    static int[,] board = new int[boardSize, boardSize];
    static bool foundSolution = false;

    static void Main()
    {
        PlaceQueens(0);
        if (!foundSolution)
        {
            Console.WriteLine("No solution found.");
        }
    }

    static void PlaceQueens(int row)
    {
        if (row == boardSize)
        {
            PrintBoard();
            foundSolution = true;
        }
        else
        {
            for (int col = 0; col < boardSize; col++)
            {
                if (IsSafe(row, col))
                {
                    board[row, col] = 1;
                    PlaceQueens(row + 1);
                    board[row, col] = 0;
                }
            }
        }
    }

    static bool IsSafe(int row, int col)
    {
        for (int i = 0; i < row; i++)
        {
            if (board[i, col] == 1)
            {
                return false;
            }
        }

        for (int i = row, j = col; i >= 0 && j >= 0; i--, j--)
        {
            if (board[i, j] == 1)
            {
                return false;
            }
        }

        for (int i = row, j = col; i >= 0 && j < boardSize; i--, j++)
        {
            if (board[i, j] == 1)
            {
                return false;
            }
        }

        return true;
    }

    static void PrintBoard()
    {
        Console.WriteLine("Solution:");
        for (int i = 0; i < boardSize; i++)
        {
            for (int j = 0; j < boardSize; j++)
            {
                Console.Write(board[i, j] + " ");
            }
            Console.WriteLine();
        }
        Console.WriteLine();
    }
}

This program finds a solution to the 8 queens problem by placing queens on a chessboard such that no two queens attack each other. It does this using a recursive algorithm that tries to place a queen on each row, starting from the top row, and backtracking when a safe position cannot be found. The program prints out the first solution it finds, or a message indicating that no solution exists.