非递归实现Python 8×8棋盘八皇后问题的空行异常调试求助

我基于Python实现8×8棋盘下的八皇后问题，运行代码后始终输出包含2个全零空行的结果。

错误输出示例：

[1, 0, 0, 0, 0, 0, 0, 0] 
[0, 0, 1, 0, 0, 0, 0, 0] 
[0, 0, 0, 0, 1, 0, 0, 0] 
[0, 1, 0, 0, 0, 0, 0, 0] 
[0, 0, 0, 0, 0, 0, 0, 0] 
[0, 0, 0, 0, 0, 0, 0, 0]
[0, 0, 0, 1, 0, 0, 0, 0]
[0, 0, 0, 0, 0, 0, 1, 0]

理想合规输出的目标皇后放置位置为：

• board[4][5] = 1
• board[5][7] = 1

相关实现要求：

• 刻意未采用递归方式实现求解函数
• 需通过现有迭代逻辑完成求解，定位代码存在的缺陷

完整Python实现代码：

def checksquares(board, row, column):
    rowtemp = row
    columntemp = column

    for i in range(0,8):                          
        if board[i][column] == 1:
            return False

    for j in range(0,8):
        if board[row][j] == 1:
            return False

    while rowtemp > 0 and columntemp > 0:          
        rowtemp = rowtemp - 1
        columntemp = columntemp - 1

    while rowtemp < 7 and columntemp < 7:          
        if board[rowtemp][columntemp] == 1:
            return False
        rowtemp = rowtemp + 1
        columntemp = columntemp + 1

    rowtemp = row
    columntemp = column

    while rowtemp > 0 and columntemp < 7:          
        rowtemp = rowtemp - 1
        columntemp = columntemp + 1

    while rowtemp < 7 and columntemp > 0:          
        if board[rowtemp][columntemp] == 1:
            return False
        rowtemp = rowtemp + 1
        columntemp = columntemp - 1

    return True


def placequeens(board, queencount):
    temp = [0,0,0,0,0,0,0,0]
    
    for i in range(0,8):
        for j in range(temp[i],8):
            if checksquares(board, i, j) == True:
                board[i][j] = 1
                queencount = queencount + 1
                temp[i] = j
        if board[i] == [0,0,0,0,0,0,0,0]:
            board[i - 1] = [0,0,0,0,0,0,0,0]
            if temp[i - 1] < 7:
                temp[i - 1] = temp[i - 1] + 1
            elif temp[i - 1] == 7:
                temp[i - 1] = 7
            temp[i] = 0              

board = [ [0, 0, 0, 0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0, 0, 0, 0] ]

queencount = 0

placequeens(board, queencount)
print(board)

内容的提问来源于stack exchange，提问作者Tofu