Scrabble challenge: Difference between revisions
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How neat! Is it really this smiple? You make it look easy. |
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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. |
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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. |
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=== Problem Statement === |
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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: |
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<pre> |
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$ python scrabble.py ZAEFIEE |
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17 feeze |
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17 feaze |
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16 faze |
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15 fiz |
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15 fez |
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12 zee |
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12 zea |
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11 za |
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6 fie |
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6 fee |
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6 fae |
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5 if |
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5 fe |
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5 fa |
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5 ef |
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2 ee |
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2 ea |
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2 ai |
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2 ae |
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</pre> |
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===Resources=== |
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* http://www.isc.ro/lists/sowpods.zip contains all words in the official [http://en.wikipedia.org/wiki/SOWPODS SOWPODS] word list, one word per line. |
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* Here is a dictionary containing all letters and their Scrabble values: |
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<pre> |
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scores = {"a": 1, "c": 3, "b": 3, "e": 1, "d": 2, "g": 2, |
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"f": 4, "i": 1, "h": 4, "k": 5, "j": 8, "m": 3, |
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"l": 1, "o": 1, "n": 1, "q": 10, "p": 3, "s": 1, |
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"r": 1, "u": 1, "t": 1, "w": 4, "v": 4, "y": 4, |
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"x": 8, "z": 10} |
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</pre> |
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===Breaking down the problem=== |
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====Step 1: construct a word list==== |
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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. |
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<b>Step 1 resources</b>: |
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<ul> |
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<li> |
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File input and output: http://docs.python.org/tutorial/inputoutput.html#reading-and-writing-files. |
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</li> |
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<li> |
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Stripping characters (like whitespace and newlines) from a string: http://docs.python.org/library/stdtypes.html#str.strip. |
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</li> |
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</ul> |
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====Step 2: get the rack==== |
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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. |
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<b>Step 2 resources</b>: |
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<ul> |
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<li> |
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Command line argument parsing: http://docs.python.org/library/argparse.html#module-argparse. |
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</li> |
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<li> |
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Getting and checking the number of command line arguments: http://docs.python.org/library/sys.html. |
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</li> |
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</ul> |
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====Step 3: find valid words==== |
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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. |
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<b>Step 3 resources</b>: |
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<ul> |
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<li> |
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List manipulation: http://docs.python.org/tutorial/datastructures.html#more-on-lists. |
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</li> |
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</ul> |
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====Step 4: scoring==== |
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Write the code to determine the Scrabble scores for each valid word, using the scores dictionary from above. |
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<b>Step 4 resources</b>: |
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<ul> |
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<li> |
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Dictionary manipulation: http://docs.python.org/tutorial/datastructures.html#dictionaries. |
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</li> |
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</ul> |
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I could watch Schildner's List and still be happy after reading this. |
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===Checking your work=== |
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What happens when you run your script on the following inputs? |
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<pre> |
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$ python scrabble.py |
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Usage: scrabble.py [RACK] |
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</pre> |
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<pre> |
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$ python scrabble.py AAAaaaa |
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2 aa |
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</pre> |
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<pre> |
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$ python scrabble.py ZZAAEEI |
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22 zeze |
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21 ziz |
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12 zee |
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12 zea |
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11 za |
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3 aia |
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2 ee |
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2 ea |
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2 ai |
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2 ae |
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2 aa |
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</pre> |
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===Bonus challenge=== |
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Modify your script to handle blank tiles. Blank tiles have a score of 0 but can be used to represent any letter. |
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===Congratulations!=== |
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You've implemented a substantial, useful script in Python from scratch. Keep practicing! |
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Revision as of 16:00, 15 January 2012
How neat! Is it really this smiple? You make it look easy.