using System;

using System.Collections.Generic;

using System.Text;

​

public class EightQueenForTest

{

    const int _Max = 8;  //八皇后

    int[] QueenPosition = new int[_Max]; //皇后放置的位置

    IList<IList<string>> result = new List<IList<string>>();

​

    public IList<IList<string>> SolveStrat(int n)

    {

        PlaceQueen(0);

        return result;

    }

    //放置皇后位置

    public void PlaceQueen(int n)

    {

        if(n == _Max)

        {

            Print();//放滿8個就輸出

            return;

        }

        for (int i = 0; i < _Max; i++)

        {

            QueenPosition[n] = i;

            if(ConflictOrNot(n))

            {

                PlaceQueen(n + 1);

            }

        }

    }

    //檢查是否有衝突

    private bool ConflictOrNot(int n)

    {

        for (int i = 0; i < n; i++)

        {

            //衝突條件

            //1. 列不重複

            //2. 斜率不能是正負1

            //3. 行不重複(一行一行放不會有此情形)

            if (QueenPosition[i] == QueenPosition[n] || Math.Abs(n - i) == Math.Abs(QueenPosition[n] - QueenPosition[i]))

            {

                return false;

            }

        }

        return true;

    }

    //輸出結果圖

    private void Print()

    {

        List<string> solution = new List<string>();

        for (int i = 0; i < _Max; i++)

        {

            StringBuilder output = new StringBuilder();     

            for (int j = 0; j < _Max; j++)

            {

                if (j == QueenPosition[i])

                {

                    output.Append("Q");

                }

                else

                {

                    output.Append(".");

                }

            }

            solution.Add(output.ToString());

        }

        result.Add(solution);

    }

}

​

public class Program

{

    public static void Main()

    {

        IList<IList<string>> result = new List<IList<string>>();

        EightQueenForTest EightQueen = new EightQueenForTest();

        result = EightQueen.SolveStrat(0);

        int i = 1;

        foreach(var first in result)

        {   

            Console.WriteLine("//Solution {0}", i++);

​

            foreach(var second in first )

            {

                Console.WriteLine(second);

            }

            Console.WriteLine();

        }

    }

}