Number spiral diagonals
AUTHOR
Shlomi Fish
http://projecteuler.net/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?
use v6;
my Int $sum = 0;
my Int $num = 1;
$sum += $num;
for 2, 4 ... 1000 -> $step {
for 0 .. 3 {
$num += $step;
$sum += $num;
}
}
say $sum;
# vim: expandtab shiftwidth=4 ft=perl6