#!/usr/bin/perl -w
#
#  "Loop Abstraction Via Recursion"
#
#   060111 by liverpole
#

# Strict
use strict;
use warnings;


# User-defined
my @list    = qw( 1 2 3 4 5 );

# Prototypes
sub abstract_loop($$$);
sub arbitrary_N_loops($;$$);
sub show_results($$$);


# Globals
my $N;                  # The number of loops (which we want to abstract)
my $total;              # Total match attempts
my $pvals = [ ];        # The list of values
my $nmatch = 0;         # Total matches


# Subroutines
sub match(@) {
    my ($plist) = @_;
    my $sum = 0;
    my $prod = 1;
    map { $prod *= $_; $sum += $_ } @$plist;
    my $div = ($prod / $sum);
    ($div == int($div));
}


sub show_results($$$) {
    my ($nloops, $nmatch, $total) = @_;
    my $pct = ($total)? int(1000 * $nmatch / $total) / 10: 0;
    my $s = (1 == $nloops)? " ": "s";
    printf "[%3d loop$s]  ", $nloops;
    printf "Matches:  %8d / %9d ", $nmatch, $total;
    printf "(%5.1f%%)\n", $pct;
}


# Main program

# One loop
$N = 1;
$nmatch = $total = 0;
foreach (@list) {
    push @$pvals, $_;               # Add a new value to the list
    match($pvals) and ++$nmatch;    # Check if it matches the criteria
    ++$total;                       # Add 1 to the total count
    pop @$pvals;                    # Remove the value at the end
}
show_results($N, $nmatch, $total);