编辑代码

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

while (my $input = <STDIN>) {
    chomp $input;
    my @chars = split //, $input;
    for (my $i = 0; $i < @chars; $i += 2) {
        if ($i + 1 < @chars) {
            ($chars[$i], $chars[$i + 1]) = ($chars[$i + 1], $chars[$i]);
        }
    }
    print join('', @chars), "\n";
}