/* Euler #28 in Picat. Problem 28 """ Starting with the number 1 and moving to the right in a clockwise direction a 5 by 5 spiral is formed as follows: 21 22 23 24 25 20 7 8 9 10 19 6 1 2 11 18 5 4 3 12 17 16 15 14 13 It can be verified that the sum of the numbers on the diagonals is 101. What is the sum of the numbers on the diagonals in a 1001 by 1001 spiral formed in the same way? """ This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com See also my Picat page: http://www.hakank.org/picat/ */ main => go. go => time(euler28). euler28 => S = 1, N = 3, while (N <= 1001) S := S + 4 * N**2 - 6 * N + 6, N := N + 2 end, println(S).