This is one of the OLD POTM problems

Long version of the problem.
The announcement of the winners and scores
Descriptions of all the entries
The consolation prizes
Some of the MATH from the participants
These are the squares I used for the finals

Program Source for primeval.c
Program Source for pringle.c
Program Source for wookin_po_nubbas.c

Back to the list of problems.

Short Problem Description

january, 1995
               T H E   P R I M E   T I M E   P O T M

  Your task is to play "connect the digits" to find prime numbers in
         a square of numbers that I provide to your program!

Find the largest prime in the square that is less than 10^9 (1,000,000,000),
and do it quickly, and you could be the next POTM winner!  (speed, rather
than program size, will be the tie-breaker this time around ....)

Primes may be up to 9 digits long ..... (less than 1,000,000,000)

Input is a 5x5 square of numbers presented at run time ... for example:

		1 9 4 0 3	legal answers:
		7 5 8 3 3	  1940339  (meanders around the edge)
		0 0 0 7 9	943485497  (re-uses several digits legally)
		0 0 0 0 0 	900000011  (many paths yield this one)
		9 0 0 1 1	       37  (hey - at least it's legal!)

***  those of you with sharp eyes will notice that "37" now appears in the
***  grid ... this was my error in the initial mailing ... my thanks to
***  the MANY of you who pointed out my error>

Make your own free website on