#!/usr/bin/env perl
use 5.010;
use warnings;
use strict;

# Initialize %votes: map animals to their number of votes.
my @animals
    = qw/alligator bear cat dog elephant fox giraffe hippo iguana jellyfish/;
my $votes   = 100;            # start with 100 votes for first word
my $decr    = int( $votes / (@animals) ); # evenly decrease # of votes
my $sum     = 0;              # grand total of votes for all words
my %votes = map
    {my $n = $votes; $sum += $n; $votes -= $decr; ( $_, $n )}
    @animals;

# Display animals and votes
print '===> ';
printf "%s:%3d ", $_, $votes{$_} for sort keys %votes;
print "  Total votes=$sum";

# Get random selections
my %popular;
my %impartial;
my %unpopular;
for ( 1 .. $sum ) {
    $popular{ popular() }++;       # should tend toward the popular
    $impartial{ impartial() }++;   # should be equally distributed
    $unpopular{ unpopular() }++;   # should tend toward the unpopular
}

# Display distribution of votes from each method
print "\nPOP: ";
printf "%s:%3d ", $_, $popular{$_}//0
    for sort keys %votes;

print "\nIMP: ";
printf "%s:%3d ", $_, $impartial{$_}//0
    for sort keys %votes;

print "\nUNP: ";
printf "%s:%3d ", $_, $unpopular{$_}//0
    for sort keys %votes;
say '';

# Method 1: choose randomly with preference for higher vote-getters
sub popular {
    my $rand = int( rand $sum );
    for my $key (
        # sort { ($votes{$b} <=> $votes{$a}) } #unnecessary
        keys %votes ) {
        return $key if ( $rand -= $votes{$key} ) <= 0;
    }
    die 'popular bug';
}

# Method 2: choose randomly without regard for popularity
sub impartial {
    return ( keys %votes )[ rand keys %votes ];
}

# Method 3: choose randomly with preference for lower vote-getters
sub unpopular {
    return '?';
}