Write an algorithm to create word ladders such as any of the following:
hard bard bird bind bins
hard ward word wood wool
hard herd head dead dean
hard hand band bind bins
hard harp hasp wasp wisp

where a word is given which must be transformed into some other word (not specified in advance) with the same number of letters, but each letter position changed from its original value, in as many steps as there are letters in the word, each step also being a valid word. This is similar to the various Word Meld puzzles on this site, except there are as many steps as there are letters in the word and each letter is changed, with each letter position being changed exactly once.

Input consists of the starting word only. It is assumed that the number of steps will be the same as the number of letters in the word. Available are files containing lists of words of any given length; call one such file, say WORDS5.TXT containing a list of words of 5 letters each, and so on. The program will find all the eligible word ladders given the words in the list.

The program will, of course, terminate without finding any results if in fact a word ladder cannot be constructed starting with the input word.

(In reply to can someone review this by Surender Taalla)

The algorithm given changes the word from left to right. If there is no word that differs from the original word only in the first letter, the QUIT is taken in step 7. Thus ladders such as "hard hand band bind bins" would not be found, as the first change there is in the third letter.

Also, the algorithm stops upon reaching the end of the length of the word, in step 18, without looking for more ladders.

It's uncertain, though, what it will do as step 10's goto is not completed. Presumably it's 14.

Posted by Charlie on 2004-01-15 21:13:41