"quot"改编自http://www.prasannatech.net/2012/07/eight-queens-python.html作者：S.Prasanna
There are many other solutions to this problem available online. This one
is quite easy to understand.
Make sure to credit other peoples code when used - and it is not acceptable to use
other peoples code as the entire solution for your assignments!!!
"quot">
board = [] size = 8
#A function which checks if a particular row and col is dangerous (i.e.,
#queen could be taken if placed there)
def danger(row, col):
""" Return if there is a danger by placing queen in
a given row, col
"""
for (i, j) in board:
if row == i: return True
if col == j: return True
if abs(row - i) == abs(col - j): return True
return False
#A function which calculates the whole solution
def placequeen(row):
#If row is bigger than size, we've finished - so print answer
if row > size:
print(board)
#If size <= row we still have more to place
else:
#try placing queen
for col in range(1, size + 1):
#is it safe?
if not danger(row, col):
board.append((row, col))
placequeen(row + 1)
board.remove((row,col))
#Run the main method, starts by plaing the first queen
placequeen(1)
为什么board.append后面跟着board.remove？这不是对名单没有任何作用吗？
您的问题的答案是，是的，它确实撤消了刚刚完成的操作，但介于两者之间的placequeen将打印出介于它们之间的每个解决方案。因此，在带有board.append((row，col((的板上放置一个queen，然后打印出该配置的每个解决方案，因为该函数是递归的，然后删除queen，以便可以尝试其他选项。