#!/usr/bin/perl

use strict;
use warnings;
use Benchmark qw( timethese cmpthese );

my @doCount = (0);           # total loops until unique array generated
my $range = 120;             # numbers range from 0 to $range
my $aSize = 1000000;         # random pool array size
my $uSize = 100;             # unique array size
my ( @grep, @map, @smart );
my @nums = arrGen();         # generate huge pool of random numbers

my $r = timethese( 2500, {
    grepGen  => sub{ @grep  = grepGen();  },
    mapGen   => sub{ @map   = mapGen();   },
    smartGen => sub{ @smart = smartGen(); },
} );
# show results
cmpthese $r;
print "loop counts - grep: $doCount[0], map: $doCount[1], smart: $doCount[2]\n";
print "array sizes - num: ",  scalar(@nums),  # should all == $uSize
                 "; grep: ",  scalar(@grep),
                 "; map: ",   scalar(@map),
                 "; smart: ", scalar(@smart), "\n";
# show sorted generated arrays to check for a rare duplicate
print "grep:\n@{[sortIt(@grep)]}\nmap:\n@{[sortIt(@map)]}\nsmart:\n@{[sortIt(@smart)]}\n";

sub arrGen {
    my @nArray;
    for ( 1..$aSize ) {
        my $rInt = int(rand($range));
        push @nArray, $rInt;
    }
    return @nArray;
}

sub sortIt {
    return sort { $a <=> $b } @_;
}

sub grepGen {
    my $idx = 0;
    my @gArray;
    for ( 1..$uSize ) {
        $doCount[0]++;
        my $rInt = $nums[$idx++];
        redo if ( @gArray && grep { /$rInt/ } @gArray );
        push @gArray, $rInt;
    }
    return @gArray;
}

sub mapGen {
    my $idx = 0;
    my @mArray;
    for ( 1..$uSize ) {
        $doCount[1]++;
        my $rInt = $nums[$idx++];
        redo if ( @mArray && map { /$rInt/ } @mArray );
        push @mArray, $rInt;
    }
    return @mArray;
}

sub smartGen {
    my $idx = 0;
    my @sArray;
    for ( 1..$uSize ) {
        $doCount[2]++;
        my $rInt = $nums[$idx++];
        redo if ( @sArray && $rInt ~~ @sArray );
        push @sArray, $rInt;
    }
    return @sArray;
}