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As always there is more than one way to do it. I see chains as arrays, so i built arrays first, then looped those to make hashes. Of coures as I wrote this and pasted I realized that this method depends on the right order, so I'm gonna make a second shot, but here is this version for fun:

#!/usr/bin/perl use strict; use warnings; use Data::Dumper; my $pairs = { (4,-1), (2,6), (6,4), (3,5), (5,-1), (99,-1), }; my @paths; foreach my $key (keys %$pairs) { my $value = $pairs->{$key}; # if the right hand side matches the start of a chain # then unshift the left onto the start of the chain my @start_path = grep { @$_[0] eq $value } @paths; unshift(@{$start_path[0]}, $key) if @start_path; # if the left hand side matches the end of a chain, # then push the left hand side onto the end my @end_path = grep { @$_[-1] eq $key } @paths; push( @{$end_path[0]}, $value) if @end_path; push @paths, [$key, $value] unless (@start_path or @end_path); } my $hh; for my $path (@paths) { my $temp = pop @$path; my $key = shift @$path; for (reverse @$path) { my $t = {$_ => $temp}; $temp = $t; } $hh->{$key} = $temp; } print Dumper($hh);

___________
Eric Hodges

In reply to Re: How to get a ideal hash by eric256
in thread How to get a ideal hash by pysome

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