Add solution for challenge-149 part 1

1 files changed, 79 insertions, 0 deletions

diff --git a/challenge-149/alexander-pankoff/perl/ch-1.pl b/challenge-149/alexander-pankoff/perl/ch-1.pl
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+#!/usr/bin/env perl
+use strict;
+use warnings;
+use feature qw'say state signatures';
+no warnings qw'experimental::signatures';
+
+# TASK #1 › Fibonacci Digit Sum
+# Submitted by: Roger Bell_West
+#
+# Given an input $N, generate the first $N numbers for which the sum of their digits is a Fibonacci number.
+# Example
+#
+# f(20)=[0, 1, 2, 3, 5, 8, 10, 11, 12, 14, 17, 20, 21, 23, 26, 30, 32, 35, 41, 44]
+
+use List::Util qw(sum0 first);
+
+run() unless caller();
+
+sub run() {
+    my ($N) = @ARGV;
+
+    if ( !$N || $N !~ m/^\d+$/ || $N < 1 ) {
+        die <<EOF;
+  Usage:
+
+    $0 N
+
+  Options:
+
+    N - a positive integer
+EOF
+    }
+
+    my @numbers = fibonacci_digit_sum($N);
+
+    say "f($N) = [" . join( ', ', @numbers ) . ']';
+
+}
+
+sub fibonacci_digit_sum($n) {
+    my @found;
+    for ( my $i = 0 ; @found < $n ; $i++ ) {
+        push @found, $i if is_fib( digit_sum($i) );
+    }
+    return @found;
+
+}
+
+sub is_fib($x) {
+    state $fibs = {
+        0 => 1,
+        1 => 1,
+
+    };
+    state $cur  = 1;
+    state $prev = 0;
+
+    while ( $x > $cur ) {
+        my $next = next_fib( $cur, $prev );
+        $prev = $cur;
+        $cur  = $next;
+
+        $fibs->{$next} = 1;
+    }
+
+    return $fibs->{$x};
+}
+
+sub digit_sum($x) {
+    my $sum = sum0 split( '', $x );
+
+    return $sum;
+}
+
+sub next_fib ( $prev, $cur ) {
+    my $next = $cur + $prev;
+
+    return $next;
+}