写了一个八皇后解法 - 木野狐(Neil Chen)

先用最笨的穷举法求解，有空再研究更好的解法：

# -*- coding: gb2312 -*-

size = 8      # 棋盘大小
EMPTY = "O"   # 空位
QUEEN = "X"   # 皇后

# 查看棋盘的信息
def show_board(cols):
    for i in range(1, size + 1):
        for j in range(1, size + 1):
            if j == cols[i]:
                print QUEEN,
            else:
                print EMPTY,
        print "\n",

# 检测棋盘上皇后摆法是否合法
# return:
#        True(不冲突), False(有冲突)
def check_board(cols):
    for i in range(1, size):
        for j in range(i + 1, size + 1):
            if (j - i) == abs(cols[j] - cols[i]):
                return False
    return True

solve_count = 0

for a in range(1, size + 1):
    for b in range(1, size + 1):
        for c in range(1, size + 1):
            for d in range(1, size + 1):
                for e in range(1, size + 1):
                    for f in range(1, size + 1):
                        for g in range(1, size + 1):
                            for h in range(1, size + 1):
                                if a <> b and a <> c and a <> d and a <> e and a <> f and a <> g and a <> h and b <> c and b <> d and b <> e and b <> f and b <> g and b <> h and c <> d and c <> e and c <> f and c <> g and c <> h and d <> e and d <> f and d <> g and d <> h and e <> f and e <> g and e <> h and f <> g and f <> h and g <> h:
                                    cols = [0,a,b,c,d,e,f,g,h]
                                    if check_board(cols):
                                        solve_count += 1
                                        show_board(cols)
                                        print "\n",

print "found %i solves." % solve_count

posted on 2006-01-08 16:40 木野狐(Neil Chen) 阅读(537) 评论(1) 编辑收藏所属分类: 编程思考、Python

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#1楼 [楼主] 2006-01-13 00:43 木野狐

参考 All Start From A Game 改进了程序，速度提高了很多，并且能计算 n 皇后问题了：

# -*- coding: gb2312 -*-

size = 8      # 棋盘大小
EMPTY = "O"   # 空位
QUEEN = "X"   # 皇后

# 查看棋盘的信息
def show_board(cols):
    for i in range(size):
        for j in range(size):
            if j == int(cols[i]) - 1:
                print QUEEN,
            else:
                print EMPTY,
        print "\n",

# 检测棋盘上皇后摆法是否合法
# return:
#        True(不冲突), False(有冲突)
def check_board(cols):
    for i in range(size - 1):
        for j in range(i + 1, size):
            if j - i == abs(int(cols[j]) - int(cols[i])):
                return False
    return True

# 得到全排列
def permute(seq):
  seqn = [ seq.pop() ]
  while seq:
    newseq = []
    new = seq.pop()
    #print "seq:",seq,'seqn', seqn ,'new', new
    for i in range(len(seqn)):
      item = seqn[i]
      for j in range(len(item)+1):
        newseq.append(''.join([item[:j],new,item[j:]]))
    seqn = newseq
    #print 'newseq',newseq
  return  seqn

if __name__ == "__main__":
    solve_count = 0
    numbers = ''.join([str(i) for i in range(1, size + 1)])

    for x in permute(list(numbers)):
        y = list(x)
        if check_board(y):
            solve_count += 1
            show_board(y)
            print "\n",

    print "found %i solves." % solve_count