Leetcode 38 Sudoku Solver

Sudoku Solver

class Solution:
    # @param {character[][]} board
    # @return {void} Do not return anything, modify board in-place instead.
    def solveSudoku(self, board):

        def check( x, y):
            temp = board[x][y]; board[x][y] = '.'
            for i in xrange(9):
                if board[i][y] == temp: return False
            for j in xrange(9):
                if board[x][j] == temp: return False
            for i in xrange(3):
                for j in xrange(3):
                    if board[(x/3)*3 + i][(y/3)*3 + j] == temp:
                        return False
            board[x][y] = temp
            return True

        def dfs(board):
            for i in xrange(9):
                for j in xrange(9):
                    if board[i][j] == '.':
                        for k in '123456789':
                            board[i][j] = k
                            if check(i, j) and dfs(board):
                                return True
                            board[i][j] = '.'
                        return False
            return True

        dfs(board)

另一种方法：http://c4fun.cn/blog/2014/03/20/leetcode-solution-02/