Py Sudoku Solver

Hello dear pythonistas!
We all know that Sudoku is a great game and in this post I am going to share with you a sudoku solver written in python. From now on you will win all Sudoku challenges :P. So without wasting any time let me share the script with you:

import sys

def same_row(i,j): return (i/9 == j/9)
def same_col(i,j): return (i-j) % 9 == 0
def same_block(i,j): return (i/27 == j/27 and i%9/3 == j%9/3)

def r(a):
  i = a.find('0')
  if i == -1:
    sys.exit(a)

  excluded_numbers = set()
  for j in range(81):
    if same_row(i,j) or same_col(i,j) or same_block(i,j):
      excluded_numbers.add(a[j])

  for m in '123456789':
    if m not in excluded_numbers:
      r(a[:i]+m+a[i+1:])

if __name__ == '__main__':
  if len(sys.argv) == 2 and len(sys.argv[1]) == 81:
    r(sys.argv[1])
  else:
    print 'Usage: python sudoku.py puzzle'
    print '  where puzzle is an 81 character string 
             representing the puzzle read left-to-right,
             top-to-bottom, and 0 is a blank'

Hey there wait! Let me share with you a shorter obfuscated version of the same Sudoku solving script. However this short version of Sudoku solver is a lot slower but I think that I should share it with you just to show you that even in python obfuscated code can be written. So here is the shorter obfuscated version:

def r(a):i=a.find('0');~i or exit(a);[m
in[(i-j)%9*(i/9^j/9)*(i/27^j/27|i%9/3^j%9/3)or a[j]for
j in range(81)]or r(a[:i]+m+a[i+1:])for m in'%d'%5**18]
from sys import*;r(argv[1])