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#!/usr/bin/perl
# Peter Campbell Smith - 2023-01-23
# PWC 201 task 2
use v5.28;
use utf8;
use warnings;
# Task: You are given an integer, $n > 0. Write a script to determine the number of ways of putting $n
# pennies in a row of piles such that each pile contains no fewer pennies than the one on its left.
# Blog: https://pjcs-pwc.blogspot.com/2023/01/201-missing-numbers-and-piles-of-pennies.html
my (@tests, $n, $ways, $piles);
@tests = (1, 2, 3, 4, 5, 20);
# loop over tests
for $n (@tests) {
# initialise
$ways = 0;
$piles = '';
# find possible ways to do it
find_ways($n, $n, '');
# output results
say qq[Input: \$n = $n\nOutput: ] . $ways;
say qq[Piles:\n$piles];
}
sub find_ways {
# returns the number of possible ways of stacking $pennies pennies in stacks no more than $height
my ($pennies, $height, $stack) = @_;
my ($h);
# no pennies left - answer found
if ($pennies == 0) {
$piles .= qq[$stack\n];
$stack = '';
$ways ++;
return;
}
# loop over possible piles
for $h (1 .. ($pennies > $height ? $height : $pennies)) {
find_ways($pennies - $h, $h, qq[$h $stack]);
}
}
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