八皇后问题学习 enumerate 和 permutations
permutations 生成123…9的全排列，共9!个
enumerate 提取横纵坐标
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| from itertools import permutations as perm | |
| # (1, 5, 8, 6, 3, 7, 2, 4)表示棋子位置：i.imgbox.com/VHrKYxDG.png | |
| cols = perm(range(1,9)) #所有可能a88=40320 | |
| # 保证对角线 | |
| def OK(s): | |
| sl = set(r-c for r,c in enumerate(s)) # y=x | |
| bs = set(r+c for r,c in enumerate(s)) # y=-x | |
| return len(sl) == len(bs) == 8 | |
| solutions = [c for c in cols if OK(c)] | |
| for i,s in enumerate(solutions,1): | |
| print i,":",s |