Ruby Alphametics Solver

I found an interesting alphametics puzzle solver from Dive Into Python 3 chapter 8.

http://www.diveintopython3.net/advanced-iterators.html#divingin

The original source is the following Python 2 code.

• Alphametics solver (Python recipe): http://code.activestate.com/recipes/576615/

I was inspired from the book and made a ruby version.

Examples

$ ruby alphametics.rb 'SEND + MORE == MONEY'
SEND + MORE == MONEY
9567 + 1085 == 10652
$ ruby alphametics.rb 'HAWAII + IDAHO + IOWA + OHIO == STATES'
HAWAII + IDAHO + IOWA + OHIO == STATES
510199 + 98153 + 9301 + 3593 == 621246
$ ruby alphametics.rb 'PI * R ** 2 == AREA' 'NORTH / SOUTH == EAST / WEST'
PI * R ** 2 == AREA
96 * 7 ** 2 == 4704
NORTH / SOUTH == EAST / WEST
51304 / 61904 == 7260 / 8760

Allows standalone zero for a solution (original python source does not).

$ ruby alphametics.rb 'MALCOLM + X == MALCOLM'
MALCOLM + X == MALCOLM
1234531 + 0 == 1234531

Testing/Benchmark

Python sources are taken from Dive Into Python 3 repository.

https://github.com/diveintomark/diveintopython3/blob/master/examples/alphametics.py

https://github.com/diveintomark/diveintopython3/blob/master/examples/alphameticstest.py

The specification of alphametics_test.rb is identical to alphameticstest.py.

$ python3 alphameticstest.py    # Python3 (borrowed from Dive Into Python 3)
.......
----------------------------------------------------------------------
Ran 7 tests in 5.134s

OK
$ rbenv local 1.9.3-p448 
$ ruby alphametics_test.rb      # Ruby 1.9.3
Run options: 

# Running tests:

.......

Finished tests in 2.551208s, 2.7438 tests/s, 2.7438 assertions/s.

7 tests, 7 assertions, 0 failures, 0 errors, 0 skips
$ rbenv local 2.0.0-p247 
$ ruby alphametics_test.rb      # Ruby 2.0.0
Loaded suite alphametics_test
Started
.......

Finished in 3.83947976 seconds.

7 tests, 7 assertions, 0 failures, 0 errors, 0 pendings, 0 omissions, 0 notifications
100% passed

1.82 tests/s, 1.82 assertions/s