偶遇八皇后问题,随即自己写了一个仅供参考

#include<stdio.h>
#include<math.h>
#define SIZE 8

void Circumsribe(int(*checkerboard)[SIZE], int x, int y, int flag);
int EightQueen(int(*checkerboard)[SIZE], int num, int begin_x, int begin_y);

void main()
{
    int checkerboard[SIZE][SIZE] = {0}, result;

    result = EightQueen(checkerboard, 8, 0, 0);
    printf_s("%d\n", result);
}

//划定或解除皇后攻击范围
void Circumsribe(int(*checkerboard)[SIZE], int x, int y, int flag)
{
    int i, j;

    for (i = 0; i < SIZE; i++)
    {
        for (j = 0; j < SIZE; j++)
        {
            if (flag == 1)
            {
                //flag为1表示放置皇后,划定攻击范围
                checkerboard[i][j] = (i == x || j == y || abs(j - y) == abs(i - x)) ? checkerboard[i][j] + 1 : checkerboard[i][j];
            }
            else
            {
                //flag为0表示移走皇后,解除攻击范围
                checkerboard[i][j] = (i == x || j == y || abs(j - y) == abs(i - x)) ? checkerboard[i][j] - 1 : checkerboard[i][j];
            }
        }
    }
}

//num表示放置皇后的序号,begin_x与begin_y表示此序号皇后放置的坐标
//返回值表示余下num个皇后有多少种允许的摆法
int EightQueen(int(*checkerboard)[SIZE], int num, int begin_x, int begin_y)
{
    int x, y, sum = 0;    //sum理解为皇后在不同位置上允许的摆法总和

    if (num <= 0 || num > SIZE || begin_x < 0 || begin_y < 0 || begin_x > SIZE || begin_y > SIZE)
    {
        //数据非法则返回0
        return 0;
    }
    else if (num == 1)
    {
        //若只有1个皇后,则从指定的(begin_x,begin_y)开始,往后统计摆法
        for (x = begin_x; x < SIZE; x++)
        {
            for (y = (x == begin_x ? begin_y : 0); y < SIZE; y++)
            {
                sum = checkerboard[x][y] == 0 ? sum + 1 : sum;
            }
        }
        return  sum;
    }
    else
    {
        //若多于1个皇后,则先将多余的皇后从指定的(begin_x,begin_y)开始摆好,在此基础上,统计最后1个皇后的摆法
        //引入(begin_x,begin_y)是为了避免重复放置,每个皇后的位置都应该从上个皇后的位置处开始,否则有重复
        for (x = begin_x; x < SIZE; x++)
        {
            for (y = (x == begin_x ? begin_y : 0); y < SIZE; y++)
            {
                if (checkerboard[x][y] == 0)
                {
                    Circumsribe(checkerboard, x, y, 1);    //若此(x,y)处可放置皇后,则划定这个皇后的攻击范围
                    sum = sum + EightQueen(checkerboard, num - 1, x, y);    //在此基础上确定余下皇后的摆法
                    Circumsribe(checkerboard, x, y, 0);    //将此皇后移到下个位置前需要先解除其攻击范围
                }
            }
        }
        return sum;
    }
}

 

posted on 2018-02-22 14:03  SHQHDMR  阅读(688)  评论(0)    收藏  举报