IMPORTANT: Please do not post solutions, hints, or other spoilers until at least 60 hours after the date of this message. Thanks. IMPORTANT: S'il vous plaît, attendez au minimum 60 heures après la date de ce message avant de poster solutions, indices ou autres révélations. Merci. BELANGRIJK: Stuur aub geen oplossingen, hints of andere tips in de eerste 60 uur na het verzendingstijdstip van dit bericht. Waarvoor dank. Qing3 Zhu4Yi4: Qing3 Ning2 Deng3Dao4 Jie1Dao4 Ben3 Xin4Xi2 Zhi1Hou4 60 Xiao3Shi2, Zai4 Fa1Biao3 Jie3Da2, Ti2Shi4, Huo4 Qi2Ta1 Hui4 Xie4Lou4 Da2An4 De5 Jian4Yi4. Xie4Xie4. ---------------------------------------------------------------- Write a program, 'wordladder', which gets two arguments, which are words of the same length, and which constructs and prints a "word ladder" from the first word to the second word. A word ladder from word AAA to word BBB is a sequence of dictionary words such that: 1. the first word in the sequence is word AAA 2. each word in the sequence after the first differs from the previous word in exactly one letter position 3. the last word in the sequence is word BBB For example, given the two words "love" and "hate", the program might print the word ladder: love hove have hate Or it might print: love lave have hate It might also print a longer word ladder, such as love lore lobe robe role rose lose lost most mosh moth math hath hate If the program is unable to find a word ladder, it should print an appropriate error message to the standard error, and exit with a failure status. The program should also accept an optional third argument, which, if specified, is the name of a dictionary file which contains the permissible words. If the third argument is omitted, the program should use a default dictionary. Sample word lists are available from http://perl.plover.com/qotw/words/