如何实现数独棋盘指定坐标所在子网格元素提取函数subgrid_values

实现思路 #

• 9x9数独按3行3列划分为9个3x3子网格，首先计算指定坐标所属子网格的边界：子网格起始行号为(r // 3) * 3，起始列号为(c // 3) * 3，覆盖起始位置往后的3行3列
• 遍历该3x3区域所有元素，过滤掉代表空位的0，收集剩余非零元素即可得到结果

完整代码实现 #

def subgrid_values(board, r, c):
    # 计算所属3x3子网格的起始行、起始列
    start_r = (r // 3) * 3
    start_c = (c // 3) * 3
    result = []
    # 遍历子网格所有元素
    for i in range(start_r, start_r + 3):
        for j in range(start_c, start_c + 3):
            if board[i][j] != 0:
                result.append(board[i][j])
    return result

测试验证 #

# 题目给出的数独棋盘
big = [
    [0, 0, 0, 0, 0, 0, 0, 0, 0],
    [4, 0, 0, 7, 8, 9, 0, 0, 0],
    [7, 8, 0, 0, 0, 0, 0, 5, 6],
    [0, 2, 0, 3, 6, 0, 8, 0, 0],
    [0, 0, 5, 0, 0, 7, 0, 1, 0],
    [8, 0, 0, 2, 0, 0, 0, 0, 5],
    [0, 0, 1, 6, 4, 0, 9, 7, 0],
    [0, 0, 0, 9, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 3, 0, 0, 0, 2]
]

print(subgrid_values(big, 4, 5))
# 输出：[3, 6, 7, 2]，和预期结果一致

内容的提问来源于stack exchange，提问作者Bryan Hii