Solution to task 1

1 files changed, 64 insertions, 0 deletions

diff --git a/challenge-149/jo-37/perl/ch-1.pl b/challenge-149/jo-37/perl/ch-1.pl
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+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+use Coro::Generator;
+use Math::Prime::Util qw(lucasu todigits vecsum);
+
+our ($examples, $base);
+$base ||= 10;
+
+run_tests() if $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [-base=B] [N]
+
+-examples
+    run the examples from the challenge
+ 
+-base=B
+    consider numbers in base B. Default: 10
+
+N
+    Print the first N numbers having a digit sum in base B that is a
+    Fibonacci number.
+
+EOS
+
+
+### Input and Output
+
+{
+    my $fib_digsum_seq = gen_fib_digsum_seq();
+    say $fib_digsum_seq->() for 1 .. shift;
+}
+
+
+### Implementation
+
+sub gen_fib_digsum_seq {
+    # Considering only numbers with a digit sum less than 233.
+    state $fib = {map +(lucasu(1, -1, $_) => undef), 0 .. 12};
+
+    # Build a generator for numbers having a digit sum that is a
+    # Fibonacci number.
+    generator {
+        for (my $k = 0;; $k++) {
+            yield $k if exists $fib->{vecsum(todigits $k, $base)};
+        }
+    }
+}
+
+
+### Examples and tests
+
+sub run_tests {
+
+    my $fib_digsum_seq = gen_fib_digsum_seq();
+    is [map $fib_digsum_seq->(), 1 .. 20],
+        [qw(0 1 2 3 5 8 10 11 12 14 17 20 21 23 26 30 32 35 41 44)],
+        'example 1';
+
+    done_testing;
+    exit;
+}