#!/usr/bin/perl -w

use strict;

use Benchmark qw(cmpthese);

{
    my $word="sigma";
    my $re  = join '.*?',
              map quotemeta,
              split (//,$word);

    sub ikegami {
        my $result=1;
        foreach my $text (
            'sigma',
            'stigma',
            'magma',
        ) {
            $result &&= ($text=~$re);
        }
    }
}

sub ikegami_noprep {
    my $word="sigma";
    my $re  = join '.*?',
              map quotemeta,
              split (//,$word);
    my $result=1;
    foreach my $text (
        'sigma',
        'stigma',
        'magma',
    ) {
        $result &&= ($text=~$re);
    }
}

{
    my $word='sigma';
    my @letters=split //,$word;
    sub findSigma {
        my $string=$_[0];
        my $index=0;
        for(my $i=0;$i<=$#letters && $index!=-1;++$i) {
            $index=index $string, $letters[$i], $index+1;
        }
        return $index!=-1;
    }
    sub rmgir {
        my $result=1;
        foreach my $text (
            'sigma',
            'stigma',
            'magma',
        ) {
            $result &&= findSigma($text);
        }
    }
}

sub findInterleavedString {
    my $string=$_[0];
    my $word=$_[1];
    my @letters=split //,$word;

    my $index=0;
    for(my $i=0;$i<=$#letters && $index!=-1;++$i) {
        $index=index $string, $letters[$i], $index+1;
    }
    return $index!=-1;
}

sub rmgir_noprep {
    my $result=1;
    foreach my $text (
        'sigma',
        'stigma',
        'magma',
    ) {
        $result &&= findInterleavedString($text, 'sigma');
    }
}

cmpthese -3, { 
                ikegami => \&ikegami,
                ikegami_noprep => \&ikegami_noprep,
                rmgir => \&rmgir,
                rmgir_noprep => \&rmgir_noprep,
             };
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