simple sudoku solver

sudoku.py

#!/usr/bin/python
# -*- coding:utf-8 -*-
import sys
def parse(s):
    return list(map(lambda c : 0 if c == ' ' else ord(c) - ord('0'), s))
board = [parse(input()) for i in range(9)]
# s = input()
# board = [parse(s[i * 9 : i * 9 + 9]) for i in range(9)]
# input()
# answer = [parse(input()) for i in range(9)]
remain = [9] * 9
for x in range(9):
    for y in range(9):
        e = board[x][y] 
        if e == 0:
            continue
        remain[e - 1] -= 1

all_remain = sys.maxsize
while sum(remain) < all_remain:
    all_remain = sum(remain)

    b = [[]] * 9
    for row in range(9):
        b[row] = list(map(lambda x: 1 if x > 0 else 0, board[row]))
    for row in range(9):
        if sum(b[row]) == 8:
            val = sum(range(1, 10)) - sum(board[row])
            board[row][b[row].index(0)] = val
            remain[val - 1] -= 1
            break

    def col_to_line(matrix, col):
        return list(map(lambda x: x[col], matrix))

    for col in range(9):
        if sum(col_to_line(b, col)) == 8:
            val = sum(range(1, 10)) - sum(col_to_line(board, col))
            board[col_to_line(b, col).index(0)][col] = val
            remain[val - 1] -= 1
            break

    def block_to_line(maxtrix, index):
        x = index // 3 * 3
        y = index % 3 * 3
        return matrix[x][y : y + 3] + matrix[x + 1][y : y + 3] \
                                    + matrix[x + 2][y : y + 3]

    for i in range(1, 10):
        if remain[i - 1] == 0:
            continue
        b = [[]] * 9
        for row in range(9):
            if i in board[row]: # 此行有该元素，此行赋1
                b[row] = [1] * 9
            else: # 此行空白处赋0
                b[row] = list(map(lambda x: 1 if x > 0 else 0, board[row]))
        for col in range(9):
            for row in range(9):
                if i != board[row][col]:
                    continue
                for r in range(9): # 此列有该元素，此列赋1
                    b[r][col] = 1
                for r in range(row // 3 * 3, row // 3 * 3 + 3): # 此块赋1
                    for c in range(col // 3 * 3, col // 3 * 3 + 3):
                        b[r][c] = 1

        def doit(b):
            for row in range(9):
                if sum(b[row]) == 8:
                    return row, b[row].index(0)
            for col in range(9):
                column = list(map(lambda x: x[col], b))
                if sum(column) == 8:
                    return column.index(0), col
            return -1, -1

        row, col = doit(b)
        if row != -1:
            board[row][col] = i
            remain[i - 1] -= 1
            break

for row in range(9):
    for col in range(9):
        if col % 3 == 0:
            print('|', end="")
        print(board[row][col], end="")
    print("")
    if row % 3 == 2:
        print("-")

if all_remain > 0:
    print("remain: %s"%str(remain))

running on python 3