我正在尝试编写一些代码来完成关于代码战link的练习
我要做的一部分工作是遍历代表数独网格的列表列表，并用可能的数字列表替换0。
我的问题是，即使我使用list.copy（）来保存原始拼图，我对原始列表（而非副本）所做的任何更改仍会更改副本。
这怎么可能？
下面是我的代码：
def sudoku(puzzle):
# copy the puzzle to be able to save original positions that are changeable
pc = puzzle.copy()
puzzle = pns(puzzle)
return puzzle
def pns(puzzle):
for y in range(len(puzzle)):
for x in range(len(puzzle[0])):
pn = set(range(1,len(puzzle) + 1))
for row_idx in range(len(puzzle)):
for col_idx in range(len(puzzle[row_idx])):
skip_bool = True
if puzzle[y][x] != 0 and type(puzzle[y][x]) == type(1):
skip_bool = False
if row_idx == y and col_idx != x and type(puzzle[row_idx][col_idx]) != type([0]):
if puzzle[row_idx][col_idx] in pn:
pn.remove(puzzle[row_idx][col_idx])
if col_idx == x and row_idx != y and type(puzzle[row_idx][col_idx]) != type([0]):
if puzzle[row_idx][col_idx] in pn:
pn.remove(puzzle[row_idx][col_idx])
pn = list(pn)
if len(pn) == 1:
puzzle[y][x] = pn[0]
elif len(pn) == 0:
puzzle[y][x] = False
elif skip_bool:
puzzle[y][x] = pn
return puzzle
预期的输出：
print(pc)
print(puzzle)
[5, 3, 0, 0, 7, 0, 0, 0, 0]
[6, 0, 0, 1, 9, 5, 0, 0, 0]
[0, 9, 8, 0, 0, 0, 0, 6, 0]
[8, 0, 0, 0, 6, 0, 0, 0, 3]
[4, 0, 0, 8, 0, 3, 0, 0, 1]
[7, 0, 0, 0, 2, 0, 0, 0, 6]
[0, 6, 0, 0, 0, 0, 2, 8, 0]
[0, 0, 0, 4, 1, 9, 0, 0, 5]
[0, 0, 0, 0, 8, 0, 0, 7, 9]
[5, 3, [1, 2, 4, 6, 9], [2, 6, 9], 7, [1, 2, 4, 6, 8], [1, 4, 6, 8, 9], [1, 2, 4, 9], [2, 4, 8]]
[6, [2, 4, 7, 8], [2, 3, 4, 7], 1, 9, 5, [3, 4, 7, 8], [2, 3, 4], [2, 4, 7, 8]]
[[1, 2, 3], 9, 8, [2, 3, 5, 7], [3, 4, 5], [1, 2, 4, 7], [1, 3, 4, 5, 7], 6, [2, 4, 7]]
[8, [1, 2, 4, 5, 7], [1, 2, 4, 5, 7, 9], [2, 5, 7, 9], 6, [1, 2, 4, 7], [1, 4, 5, 7, 9], [1, 2, 4, 5, 9], 3]
[4, [2, 5, 7], [2, 5, 6, 7, 9], 8, 5, 3, [6, 7, 9], [2, 9], 1]
[7, [1, 4, 5, 8], [1, 3, 4, 5, 9], [3, 5, 9], 2, [1, 4, 8], [1, 3, 4, 5, 8, 9], [1, 3, 4, 5, 9], 6]
[[1, 3, 9], 6, [1, 3, 4, 5, 7, 9], [3, 5, 7, 9], [3, 4], [1, 4, 7], 2, 8, [4, 7]]
[[2, 3], [2, 7, 8], [2, 3, 6, 7], 4, 1, 9, [3, 6, 7, 8], [2, 3], 5]
[[1, 2, 3], [1, 2, 4, 5], [1, 2, 3, 4, 5, 6], [2, 3, 5, 6], 8, [1, 2, 4, 6], [1, 3, 4, 5, 6], 7, 9]
我实际上得到的是第二个列表的2个副本。