Python 即使使用复制方法也无故更改列表

Question

def return_solved_board(board):
    solution = board.copy()

回溯递归循环开始

def solve(board): 
    for y in range(9):
        for x in range(9):
            if solution[y][x] == 0:
                for number in range(1,10):
                    if check_rules_at_point(x, y, number, solution):
                        solution[y][x] = number
                        solve(solution)
    #Where backtracking comes into play, if the solve method fails on the next cell than it resets current one.
                        solution[y][x] = 0
    #Breaks out of recursion to try a differant number in cell prior
                return
    #Stores a solved copy of the solution into global variable
    global returned_information
    returned_information = solution.copy()
    print(returned_information) #1st print statement

检查板子是否可以解决

if not check_for_valid_board(board):
    return "This board is not possible to solve."
else:
    solve(board)
    global returned_information
    print(returned_information) #2nd print statement
    return returned_information

print(return_solved_board(valid_sudoku_board1))

我正在尝试编写一个解决数独谜题的程序。拼图存储在列表列表中。当我运行这个程序的第一个打印语句 returns 是正确解决的列表列表。但是，第二个 return 语句 return 是原始未解之谜。他们的两个 id 是相同的但是我不明白为什么 returned_information 在第二个打印语句中变回 returned_information 只被调用一次。

Answer 1

您可能遇到了字典/列表 copy() 是一个浅拷贝；使用 copy.deepcopy(...) 而不是进行深拷贝。

Python 即使使用复制方法也无故更改列表

Python list changing for no reason even with copy method

python

recursion

list

backtracking

回溯递归循环开始

检查板子是否可以解决