Wordiff is an original game in which contestants take turns spelling new dictionary words that only differ from the last by a change in one letter.

Wordiff is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

The change can be either:

  1. a deletion of one letter;
  2. addition of one letter;
  3. or change in one letter.

Note:

  • All words must be in the dictionary.
  • No word in a game can be repeated.
  • The first word must be three or four letters long.
Task

Create a program to aid in the playing of the game by:

  • Asking for contestants names.
  • Choosing an initial random three or four letter word from the dictionary.
  • Asking each contestant in their turn for a wordiff word.
  • Checking the wordiff word is:
  • in the dictionary,
  • not a repetition of past words,
  • and differs from the last appropriately.
Optional stretch goal

Add timing.

  • Allow players to set a maximum playing time for the game.
  • An internal timer accumulates how long each user takes to respond in their turns.
  • Play is halted if the maximum playing time is exceeded on a players input.
  • That last player must have entered a wordiff or loses.
  • If the game is timed-out, the loser is the person who took the longest `average` time to answer in their rounds.

Nim

Translation of: Python

<lang Nim>import httpclient, sequtils, sets, strutils, sugar from unicode import capitalize

const

 DictFname = "unixdict.txt"
 DictUrl1 = "http://wiki.puzzlers.org/pub/wordlists/unixdict.txt"    # ~25K words
 DictUrl2 = "https://raw.githubusercontent.com/dwyl/english-words/master/words.txt"  # ~470K words


type Dictionary = HashSet[string]


proc loadDictionary(fname = DictFname): Dictionary =

 ## Return appropriate words from a dictionary file.
 for word in fname.lines():
   if word.len >= 3 and word.allCharsInSet(Letters): result.incl word.toLowerAscii


proc loadWebDictionary(url: string): Dictionary =

 ## Return appropriate words from a dictionary web page.
 let client = newHttpClient()
 for word in client.getContent(url).splitLines():
   if word.len >= 3 and word.allCharsInSet(Letters): result.incl word.toLowerAscii


proc getPlayers(): seq[string] =

 ## Return inputted ordered list of contestant names.
 try:
   stdout.write "Space separated list of contestants: "
   stdout.flushFile()
   result = stdin.readLine().splitWhitespace().map(capitalize)
   if result.len == 0:
     quit "Empty list of names. Quitting.", QuitFailure
 except EOFError:
   echo()
   quit "Encountered end of file. Quitting.", QuitFailure


proc isWordiffRemoval(word, prev: string; comment = true): bool =

 ## Is "word" derived from "prev" by removing one letter?
 for i in 0..prev.high:
   if word == prev[0..<i] & prev[i+1..^1]: return true
 if comment: echo "Word is not derived from previous by removal of one letter."
 result = false


proc isWordiffInsertion(word, prev: string; comment = true): bool =

 ## Is "word" derived from "prev" by adding one letter?
 for i in 0..word.high:
   if prev == word[0..<i] & word[i+1..^1]: return true
 if comment: echo "Word is not derived from previous by insertion of one letter."
 return false


proc isWordiffChange(word, prev: string; comment = true): bool =

 ## Is "word" derived from "prev" by changing exactly one letter?
 var diffcount = 0
 for i in 0..word.high:
   diffcount += ord(word[i] != prev[i])
 if diffcount != 1:
   if comment:
     echo "More or less than exactly one character changed."
   return false
 result = true


proc isWordiff(word: string; wordiffs: seq[string]; dict: Dictionary; comment = true): bool =

 ## Is "word" a valid wordiff from "wordiffs[^1]"?
 if word notin dict:
   if comment:
     echo "That word is not in my dictionary."
     return false
 if word in wordiffs:
   if comment:
     echo "That word was already used."
     return false
 result = if word.len < wordiffs[^1].len: word.isWordiffRemoval(wordiffs[^1], comment)
          elif word.len > wordiffs[^1].len: word.isWordiffInsertion(wordiffs[^1], comment)
          else: word.isWordiffChange(wordiffs[^1], comment)


proc couldHaveGot(wordiffs: seq[string]; dict: Dictionary): seq[string] =

 for word in dict - wordiffs.toHashSet:
   if word.isWordiff(wordiffs, dict, comment = false):
     result.add word


when isMainModule:

 import random
 randomize()
 let dict = loadDictionary(DictFname)
 let dict34 = collect(newSeq):
                for word in dict:
                  if word.len in [3, 4]: word
 let start = sample(dict34)
 var wordiffs = @[start]
 let players = getPlayers()
 var iplayer = 0
 var word: string
 while true:
   let name = players[iplayer]
   while true:
     stdout.write "$1, input a wordiff from “$2”: ".format(name, wordiffs[^1])
     stdout.flushFile()
     try:
       word = stdin.readLine().strip()
       if word.len > 0: break
     except EOFError:
       quit "Encountered end of file. Quitting.", QuitFailure
   if word.isWordiff(wordiffs, dict):
     wordiffs.add word
   else:
     echo "You have lost, $#.".format(name)
     let possibleWords = couldHaveGot(wordiffs, dict)
     if possibleWords.len > 0:
       echo "You could have used: ", possibleWords[0..min(possibleWords.high, 20)].join(" ")
     break
   iplayer = (iplayer + 1) mod players.len</lang>
Output:
Space separated list of contestants: Paddy Maggie
Paddy, input a wordiff from “beta”: bet
Maggie, input a wordiff from “bet”: bee
Paddy, input a wordiff from “bee”: tee
Maggie, input a wordiff from “tee”: teen
Paddy, input a wordiff from “teen”: teeny
That word is not in my dictionary.
You have lost, Paddy.
You could have used: then steen tern keen teem teet been seen ten


Python

This is without timing, but ends by showing some wordiffs from the dictionary that could have worked on failure. <lang python># -*- coding: utf-8 -*-

from typing import List, Tuple, Dict, Set from itertools import cycle, islice from collections import Counter import re import random import urllib

dict_fname = 'unixdict.txt' dict_url1 = 'http://wiki.puzzlers.org/pub/wordlists/unixdict.txt' # ~25K words dict_url2 = 'https://raw.githubusercontent.com/dwyl/english-words/master/words.txt' # ~470K words

word_regexp = re.compile(r'^[a-z]{3,}$') # reduce dict words to those of three or more a-z characters.


def load_dictionary(fname: str=dict_fname) -> Set[str]:

   "Return appropriate words from a dictionary file"
   with open(fname) as f:
       return {lcase for lcase in (word.strip().lower() for word in f)
               if word_regexp.match(lcase)}

def load_web_dictionary(url: str) -> Set[str]:

   "Return appropriate words from a dictionary web page"
   words = urllib.request.urlopen(url).read().decode().strip().lower().split()
   return {word for word in words if word_regexp.match(word)}


def get_players() -> List[str]:

   "Return inputted ordered list of contestant names."
   names = input('Space separated list of contestants: ')
   return [n.capitalize() for n in names.strip().split()]

def is_wordiff(wordiffs: List[str], word: str, dic: Set[str], comment=True) -> bool:

   "Is word a valid wordiff from wordiffs[-1] ?"
   if word not in dic:
       if comment: 
           print('That word is not in my dictionary')
       return False
   if word in wordiffs:
       if comment: 
           print('That word was already used.')
       return False
   if len(word) < len(wordiffs[-1]):
       return is_wordiff_removal(word, wordiffs[-1], comment)
   elif len(word) > len(wordiffs[-1]):
       return is_wordiff_insertion(word, wordiffs[-1], comment)
   
   return is_wordiff_change(word, wordiffs[-1], comment)


def is_wordiff_removal(word: str, prev: str, comment=True) -> bool:

   "Is word derived from prev by removing one letter?"
   ...
   ans = word in {prev[:i] + prev[i+1:] for i in range(len(prev))}
   if not ans:
       if comment: 
           print('Word is not derived from previous by removal of one letter.')
   return ans


def is_wordiff_insertion(word: str, prev: str, comment=True) -> bool:

   "Is word derived from prev by adding one letter?"
   diff = Counter(word) - Counter(prev)
   diffcount = sum(diff.values())
   if diffcount != 1:
       if comment: 
           print('More than one character insertion difference.')
       return False
   
   insert = list(diff.keys())[0] 
   ans =  word in {prev[:i] + insert + prev[i:] for i in range(len(prev) + 1)}
   if not ans:
       if comment: 
           print('Word is not derived from previous by insertion of one letter.')
   return ans


def is_wordiff_change(word: str, prev: str, comment=True) -> bool:

   "Is word derived from prev by changing exactly one letter?"
   ...
   diffcount = sum(w != p for w, p in zip(word, prev))
   if diffcount != 1:
       if comment: 
           print('More or less than exactly one character changed.')
       return False
   return True

def could_have_got(wordiffs: List[str], dic: Set[str]):

   return (word for word in (dic - set(wordiffs)) 
           if is_wordiff(wordiffs, word, dic, comment=False))

if __name__ == '__main__':

   dic = load_web_dictionary(dict_url2)
   dic_3_4 = [word for word in dic if len(word) in {3, 4}]
   start = random.choice(dic_3_4)
   wordiffs = [start]
   players = get_players()
   for name in cycle(players):
       word = input(f"{name}: Input a wordiff from {wordiffs[-1]!r}: ").strip()
       if is_wordiff(wordiffs, word, dic):
           wordiffs.append(word)
       else:
           print(f'YOU HAVE LOST {name}!')
           print("Could have used:", 
                 ', '.join(islice(could_have_got(wordiffs, dic), 10)), '...')
           break</lang>
Output:
Space separated list of contestants: Paddy Maggie

Paddy: Input a wordiff from 'sett': sets

Maggie: Input a wordiff from 'sets': bets

Paddy: Input a wordiff from 'bets': buts

Maggie: Input a wordiff from 'buts': bits

Paddy: Input a wordiff from 'bits': bit

Maggie: Input a wordiff from 'bit': bite

Paddy: Input a wordiff from 'bite': biter

Maggie: Input a wordiff from 'biter': bitter

Paddy: Input a wordiff from 'bitter': sitter

Maggie: Input a wordiff from 'sitter': titter

Paddy: Input a wordiff from 'titter': tutter
That word is not in my dictionary
YOU HAVE LOST Paddy!
Could have used: titfer, witter, tittery, totter, titler, kitter, twitter, tilter, gitter, jitter ...