Special Pythagorean triplet
AUTHOR
Gerhard R
https://projecteuler.net/problem=9
A Pythagorean triplet is a set of three natural numbers, a < b < c, for which,
a^2 + b^2 = c^2
For example, 3^2 + 4^2 = 9 + 16 = 25 = 5^2.
There exists exactly one Pythagorean triplet for which a + b + c = 1000. Find the product abc.
use v6;
constant $N = 1000;
my $result;
1..Int((1 - sqrt(0.5)) * $N) \
# compute numerator and denominator of closed expression for b
==> map -> $a { [ $a, $N * ($N - 2 * $a), 2 * ($N - $a) ] } \
# check if closed expression yields an integer
==> grep -> [ $a, $u, $v ] { $u %% $v } \
# compute b and c
==> map -> [ $a, $u, $v ] { my $b = $u div $v; [ $a, $b, $N - $a - $b ] } \
# ... to give the result.
# XXX Rakudo feed operator wraps results in an extra sequence, thus .[0]
==> { .[0].say }();
# vim: expandtab shiftwidth=4 ft=perl6