21 February 2018

Another puzzle. Arranging digits

Do not write the answer in the Comments section. If you get the answer, simply message me on FB or write in the Comments section that you got it (without actually giving away the answer).

Can you come up with a 8 digited number where the digits are 1,1,2,2,3,3,4,4 and the following are true:
There are exactly 4 digits between the two “4”s in the number.
There are exactly 3 digits between the two “3”s in the number.
There are exactly 2 digits between the two “2”s in the number.
There is exactly 1 digit between the two “1”s in the number.

So, 12344321 cannot be an answer since there are 6 digits between the “1”s, 4 digits between the “2”s etc etc etc.

What is the number? (Hint: There are two answers)

Posted February 21, 2018 by Rajib Roy in category "Puzzles


  1. By Kaushik Datta on

    This is called the Langford’s problem. For example: 231213. Next assignment is to write a program to find all possible such numbers?

  2. By Rajib Roy on

    For completeness sake, here re the answers as many of you have figured out… 41312432 and 23421314

    The following had sent me the answers… Kaushik, Ritesh, Vishal, Rupa, Sourin, Asif, Ambarish, Nachiketa, Ranjan, Jishnu, Ramesh, Deepak, Kenneth, Pradeep, Madhusudhan and RipuDaman. I hope I have not missed anybody…


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