[euler/prob009] add version using feed operators

Author: gerdr

euler/prob009-gerdr-feeds.pl

@@ -0,0 +1,21 @@
+use v6;
+
+constant N = 1000;
+
+# possible range of a
+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 ] }
+
+# compute product
+==> map -> @triple { [*] @triple }
+
+# print result
+==> say;