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

my %node;
my $folder = "P:\\Prod-Operations\\Maint-Eng\\Maintenance Projects\\INF\\DB\\IFDB\\TAGHIERARCHY\\PerlScripts";
my $resultfile = "resultset.txt";
my $interset01 = "interset01.txt";
my $interset02 = "interset02.txt";

open (DATA, "< $folder\\$resultfile") || die "could not open file: $!";
while (<DATA>) {
    my ( $c, $p ) = split /\|/;
    if ( $c eq $p ) {  # these are easy, so finish them first
        print;
        next;
    }

    if ( exists( $node{$c}{child_of} )) {
        warn "$.: bad record: $c is child of both $p and $node{$c}{child_of}\n";
        next;
    }
    $node{$c}{child_of} = $p;
    $node{$p}{parent_of}{$c} = undef;
}

# begin the sorted output by looping over values that do not have parents:
# open (INT01,">$folder\\$interset01") or die "Can not open file $folder\\$interset01 for writing, quitting\n";

for my $parent ( grep {!exists( $node{$_}{child_of} ) } keys %node ) {
    my $children = $node{$parent}{parent_of};  # ref to hash of child values
    trace_down( $children, \%node );
}

sub trace_down
{
    my ( $kids, $tree ) = @_;
    for my $kid ( keys %$kids ) {
        # print INT01 "$kid|$$tree{$kid}{child_of}";
        print "$kid|$$tree{$kid}{child_of}\n";
        if ( exists( $$tree{$kid}{parent_of} )) {
            trace_down( $$tree{$kid}{parent_of}, $tree );
        }
    }
}