#!/usr/bin/env perl -l

use warnings;
use strict;
use Benchmark qw/timethese cmpthese/;
use Test::More;

my @az = ('a'..'z', 'A'..'Z', '1'..'9');    # note: if '0' is in your 
+alphabet, chop() will fail
my @golden_original;
my $N = 2000;
for( 1 .. $N ) {
    push @golden_original,  join '', (map { $az[rand @az] } 1..$N-5), 
+'0'x5;
}
#print length($str), qq(\t"$str");
#print scalar @golden_original;
                                           #diag explain org => \@gold
+en_original;
my $wcf = [with_chop_fixed(@golden_original)]; #diag explain wcf => $w
+cf;
my $wch = [with_chop      (@golden_original)]; #diag explain wch => $w
+ch;
my $wsp = [with_split     (@golden_original)]; #diag explain wsp => $w
+sp;
my $wsu = [with_substr    (@golden_original)]; #diag explain wsu => $w
+su;
is_deeply( $wch, $wsp, 'your chop vs split');
is_deeply( $wcf, $wsp, 'my chop vs split');
is_deeply( $wsu, $wsp, 'substr vs split');

sub with_split {
    my @original = @_;
    my @transposed;
    for( @original ) {
        my $i = 0;
        $transposed[$i++] .= $_ for split //;
    }
    return @transposed;
}
sub with_chop {
    my @original = @_;
    my @transposed;
    for( map $_ = reverse, @original ){
        my $i = 0;
        $transposed[ $i ++ ] .= chop while $_;
    }
    return @transposed;
}
sub with_chop_fixed {
    my @original = @_;
    my @transposed;
    for( map $_ = reverse, @original ){
        my $i = 0;
        $transposed[ $i ++ ] .= chop while length $_;
    }
    return @transposed;
}
sub with_substr {
    my @original = @_;
    my $w = scalar @original;
    my @transposed = ( ' 'x$w ) x $w;
    for my $i ( 0 .. $#original ) {
        for my $j ( 0 .. $i ) {
            substr($transposed[$i], $j, 1) = substr($original[$j], $i,
+ 1);
            substr($transposed[$j], $i, 1) = substr($original[$i], $j,
+ 1);
        }
    }
    return @transposed;
}

#my $r = timethese( -5, {
#    with_substr  => sub { with_substr( @golden_original ); },
#    with_split   => sub { with_split ( @golden_original ); },
#    with_chop    => sub { with_chop  ( @golden_original ); },
#});
#cmpthese $r;

done_testing();
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