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#!/usr/bin/perl -s
use v5.16;
use Test2::V0;
use List::Gen;
use experimental 'signatures';
our ($tests, $examples);
run_tests() if $tests || $examples; # does not return
die <<EOS unless @ARGV;
usage: $0 [-examples] [-tests] [N]
-examples
run the examples from the challenge
-tests
run some tests
N
print N's Collatz sequence
EOS
### Input and Output
# Append the final "one".
(gen_collatz(shift) + [1])->say;
### Implementation
sub gen_collatz ($n) {
# Generator for N's Collatz sequence.
iterate {$_ % 2 ? $_ * 3 + 1 : $_ / 2}->from($n)->until('== 1');
}
### Examples and tests
sub run_tests {
SKIP: {
skip "examples" unless $examples;
is gen_collatz(23)->apply, [23, 70, 35, 106, 53, 160, 80, 40,
20, 10, 5, 16, 8, 4, 2], 'example';
}
SKIP: {
skip "tests" unless $tests;
}
done_testing;
exit;
}
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