Python实现棋盘病毒模拟出现逻辑错误，如何进行修复

• 错误1：二维数组使用浅拷贝，导致新旧网格共享行数据，本轮修改的状态污染同轮邻居统计
  Python中list[:]仅实现一层浅拷贝，对于二维列表，修改新列表的子元素会同步修改原列表的对应元素，导致同轮中前面格子的更新被后面的邻居统计错误计入。
• 错误2：neighbors函数中多余的打印语句会输出大量无关的邻居计数，干扰正常结果展示
• 错误3：main函数中保存上一轮状态的last_grid也使用了浅拷贝，导致状态对比逻辑错误，误判进入无限循环

grid = [
    [0, 1, 0, 1],
    [1, 0, 0, 0],
    [0, 0, 0, 0],
    [0, 0, 0, 0]
]


def write(grid):
    """
    以0/1格式打印棋盘
    """
    for row in grid:
        for item in row:
            print(f" {item}", end="")
        print()


def neighbors(grid, i, j):
    """
    统计指定位置的上下左右四个方向的感染邻居数量
    """
    num_neighbours = 0
    if i > 0:
        if grid[i - 1][j]:
            num_neighbours = num_neighbours + 1
    if i < len(grid) - 1:
        if grid[i + 1][j]:
            num_neighbours = num_neighbours + 1
    if j > 0:
        if grid[i][j - 1]:
            num_neighbours = num_neighbours + 1
    if j < len(grid[i]) - 1:
        if grid[i][j + 1]:
            num_neighbours = num_neighbours + 1
    return num_neighbours


def update(grid):
    """
    基于上一轮棋盘状态，计算新一轮的棋盘状态，所有更新基于上一轮的原始状态，不会互相干扰
    """
    # 改为逐行深拷贝，新老棋盘完全独立
    new_board = [row[:] for row in grid]
    for i in range(len(grid)):
        for j in range(len(grid[i])):
            num_neighbours = neighbors(grid, i, j)
            if num_neighbours >= 2:
                new_board[i][j] = 1
    return new_board


def check_all_ones(a):
    """
    检查棋盘是否全部被感染
    """
    return not any(c != 1 for r in a for c in r)


def main():
    """
    运行模拟主逻辑
    """
    global grid
    print("Initial State of board:")
    print()
    write(grid)
    state_num = 1
    while True:
        # 改为逐行深拷贝，保存上一轮的完整原始状态
        last_grid = [row[:] for row in grid]
        grid = update(grid)
        state_num = state_num + 1
        print()
        print(f"State {state_num} of board:")
        print()
        write(grid)
        if check_all_ones(grid):
            print()
            print("Virus has spread to whole board.")
            break
        if grid == last_grid:
            print()
            print("Infinite loop entered.")
            break


if __name__ == "__main__":
    main()

修复后第一轮更新结果和预期完全一致：

Initial State of board:

 0 1 0 1
 1 0 0 0
 0 0 0 0
 0 0 0 0

State 2 of board:

 1 1 1 1
 1 1 0 0
 0 0 0 0
 0 0 0 0

内容的提问来源于stack exchange，提问作者Robin Andrews