Scrabble challenge

There's a huge leap between having learned the fundamentals of a programming language and being able to sit down at a blank text editor and implement an idea from scratch.

Getting over the "I sit down at a text editor with an idea -- now what?" hump takes practice! Here's a fun practice problem that provides some guidance by breaking down the implementation steps and suggesting resources.

Problem Statement

Write a Python script that takes a Scrabble rack as a command-line argument and prints all valid Scrabble words that can be constructed from that rack, along with their Scrabble scores, sorted by score. An example invocation and output:

$ python scrabble.py ZAEFIEE
17 feeze
17 feaze
16 faze
15 fiz
15 fez
12 zee
12 zea
11 za
6 fie
6 fee
6 fae
5 if
5 fe
5 fa
5 ef
2 ee
2 ea
2 ai
2 ae

Resources

• http://www.isc.ro/lists/sowpods.zip contains all words in the official SOWPODS word list, one word per line.
• Here is a dictionary containing all letters and their Scrabble values:

scores = {"a": 1, "c": 3, "b": 3, "e": 1, "d": 2, "g": 2,
         "f": 4, "i": 1, "h": 4, "k": 5, "j": 8, "m": 3,
         "l": 1, "o": 1, "n": 1, "q": 10, "p": 3, "s": 1,
         "r": 1, "u": 1, "t": 1, "w": 4, "v": 4, "y": 4,
         "x": 8, "z": 10}

Breaking down the problem

Step 1: construct a word list

Write the code to open and read the sowpods word file. Create a list, where each element is a word in the sowpods word file. Note that each line in the file ends in a newline, which you'll need to strip.

Step 1 resources:

• File input and output: http://docs.python.org/tutorial/inputoutput.html#reading-and-writing-files.
• Stripping characters (like whitespace and newlines) from a string: http://docs.python.org/library/stdtypes.html#str.strip.

Step 2: get the rack

Write the code to get the Scrabble rack from a command line argument. Handle the case where a user forgets to supply a rack. Make sure you are consistent about capitalization: if your scores dictionary is lowercase, the letters supplied by the user need to be converted to lowercase at some point before you compare them.

Step 2 resources:

• Command line argument parsing: http://docs.python.org/library/argparse.html#module-argparse.
• Getting and checking the number of command line arguments: http://docs.python.org/library/sys.html.

Step 3: find valid words

Write the code to find all words from the word list that are made of letters that are a subset of the rack letters. There are many ways to do this, but here's one way that is easy to reason about and is fast enough for our purposes: go through every word in the word list, and for every letter in that word, see if that letter is contained in the rack. If it is, save the word in a valid_words list. Make sure you handle repeat letters: once a letter from the rack has been used, it can't be used again.

Step 3 resources:

• List manipulation: http://docs.python.org/tutorial/datastructures.html#more-on-lists.

Step 4: scoring

Write the code to determine the Scrabble scores for each valid word, using the scores dictionary from above.

Step 4 resources:

• Dictionary manipulation: http://docs.python.org/tutorial/datastructures.html#dictionaries.

I could watch Schildner's List and still be happy after reading this.

Checking your work

What happens when you run your script on the following inputs?

$ python scrabble.py 
Usage: scrabble.py [RACK]

$ python scrabble.py AAAaaaa
2 aa

$ python scrabble.py ZZAAEEI
22 zeze
21 ziz
12 zee
12 zea
11 za
3 aia
2 ee
2 ea
2 ai
2 ae
2 aa

Bonus challenge

Modify your script to handle blank tiles. Blank tiles have a score of 0 but can be used to represent any letter.

Congratulations!

You've implemented a substantial, useful script in Python from scratch. Keep practicing!