If two 1's, two 2's and two 3's are arranged thus:

2 3 1 2 1 3

then the two 1's enclose 1 other digit, the two 2's enclose 2 other digits, and the two 3's enclose 3 other digits.

Can you find a similar arrangement using the seven pairs 1,1,...7,7?

The given problem admits of multiple solutions.

One of the possible arrangements is:

1 4 1 5 6 7 4 2 3 5 2 6 3 7

Posted by K Sengupta on 2007-11-24 05:46:06