#! perl -slw
use strict;

our $N ||= 1e3;
our $PRE ||= '12';

my $base = 'c:/test/700432/';

sub incPath {
    my @path = unpack 'C*', $_[ 0 ];

    my $full = $base;
    mkdir $full .= $_ . '/' for @path[ 0 .. $#path -1 ];
    $full .= $path[ -1 ] . '.count';

    if( -e $full  ) {
        open my $fh, '+<', $full or die "$! : $full";
        my $count = <$fh>;
        seek $fh, 0, 0;
        print $fh ++$count;
        close $fh;
    }
    else {
        open my $fh, '>', $full or die "$! : $full";
        print $fh 1;
        close $fh;
    }
}

sub traversePrefix {
    my( $path, $code ) = @_;

    my @path = unpack 'C*', $path;
    my $prefix = $base . join '/', @path;
    return unless -e $prefix;

    my @dirs = $prefix;
    for my $dir ( @dirs ) {
        for my $file ( glob $dir . '*' ) {
            push( @dirs, $file . '/' ), next if -d $file;
            open my $fh, '<', $file or die "$! : $file";
            chomp( my $count = scalar <$fh> );
            ( $file ) = $file =~ m[^$base(.+).count$];
            my $key = pack 'C*', split '/', $file;
            $code->( $key, $count );
        }
    }
}

sub rndStr{ join'', @_[ map{ rand @_ } 1 .. shift ] }

## Generate $N keys (paths) and incr their counts
for ( 1 .. $N ) {
    printf "\r$_\t";
    my $key = rndStr 1+int( rand 5 ), map chr, 0..255;
    incPath( $key );
}

## Traverse starting from $PRE and print out the keys and counts
traversePrefix $PRE, sub {
    print "@_";
};