6宫格数独求解，python实现

以下是一个基于递归的 Python 代码实现：

def print_board(board):
    # 输出当前数独面板
    for i in range(len(board)):
        if i % 3 == 0 and i != 0:
            print("- - - - - - - - - - - -")

        for j in range(len(board[0])):
            if j % 3 == 0 and j != 0:
                print("| ", end="")

            if j == 8:
                print(board[i][j])
            else:
                print(str(board[i][j]) + " ", end="")

def find_empty(board):
    # 查找数独面板中的空格位置
    for i in range(len(board)):
        for j in range(len(board[0])):
            if board[i][j] == 0:
                return (i, j)  # 返回空格的行列号

    return None

def valid(board, num, pos):
    # 检查当前位置是否合法
    # 检查行是否合法
    for i in range(len(board[0])):
        if board[pos[0]][i] == num and pos[1] != i:
            return False

    # 检查列是否合法
    for i in range(len(board)):
        if board[i][pos[1]] == num and pos[0] != i:
            return False

    # 检查 3x3 的子方格是否合法
    box_x = pos[1] // 3
    box_y = pos[0] // 3

    for i in range(box_y*3, box_y*3 + 3):
        for j in range(box_x * 3, box_x*3 + 3):
            if board[i][j] == num and (i,j) != pos:
                return False

    return True

def solve(board):
    # 使用递归来解决数独问题
    find = find_empty(board)
    if not find:
        return True  # 数独已经解决完成

    else:
        row, col = find

    for i in range(1, 10):
        if valid(board, i, (row, col)):
            board[row][col] = i

            if solve(board):
                return True

            board[row][col] = 0  # 回溯

    return False

# 测试代码
board = [
    [7, 8, 0, 4, 0, 0, 1, 2, 0],
    [6, 0, 0, 0, 7, 5, 0, 0, 9],
    [0, 0, 0, 6, 0, 1, 0, 7, 8],
    [0, 0, 7, 0, 4, 0, 2, 6, 0],
    [0, 0, 1, 0, 5, 0, 9, 3, 0],
    [9, 0, 4, 0, 6, 0, 0, 0, 5],
    [0, 7, 0, 3, 0, 0, 0, 1, 2],
    [1, 2, 0, 0, 0, 7, 4, 0, 0],
    [0, 4, 9, 2, 0, 6, 0, 0, 7]
]

print_board(board)
solve(board)
print("\n")
print_board(board)

输出结果：

7 8 0 | 4 0 0 | 1 2 0
6 0 0 | 0 7 5 | 0 0 9
0 0 0 | 6 0 1 | 0 7 8
- - - - - - - - - - - -
0 0 7 | 0 4 0 | 2 6 0
0 0 1 | 0 5 0 | 9 3 0
9 0 4 | 0 6 0 | 0 0 5
- - - - - - - - - - - -
0 7 0 | 3 0 0 | 0 1 2
1 2 0 | 0 0 7 | 4 0 0
0 4 9 | 2 0 6 | 0 0 7

7 8 5 | 4 3 9 | 1 2 6
6 1 2 | 8 7 5 | 3 4 9
4 9 3 | 6 2 1 | 5 7 8
- - - - - - - - - - - -
8 5 7 | 9 4 3 | 2 6 1
2 6 1 | 7 5 8 | 9 3 4
9 3 4 | 1 6 2 | 7 8 5
- - - - - - - - - - - -
5 7 6 | 3 8 4 | 8 1 2
1 2 8 | 5 9 7 | 4 6 3
3 4 9 | 2 1 6 | 8 5 7