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Re^2: find all paths of length n in a graph

by Roy Johnson (Monsignor)
on Jan 10, 2006 at 20:47 UTC ( #522312=note: print w/replies, xml ) Need Help??

in reply to Re: find all paths of length n in a graph
in thread find all paths of length n in a graph

Algorithm::Loops' NestedLoops allows a non-recursive implementation:
use Algorithm::Loops 'NestedLoops'; sub find_path { my ($adj_list, $length) = @_; my %been_there; NestedLoops([ [sort {$a <=> $b} keys %$adj_list], (sub { # The last value on @_ has just changed, so remove it from %be +en_there # and set the new one my ($last_position, $last_value) = ($#_, $_[-1]); delete $been_there{$_} for grep $been_there{$_} >= $last_posit +ion, keys %been_there; $been_there{$last_value} = $last_position; # Here I grep out the already-visited nodes, but you could als +o exclude # any letters that don't result in prefixes of real words. [ grep !defined($been_there{$_}), @{$adj_list->{$last_value}} +] }) x ($length-1)] ); } my $i = find_path(\%adjacency_list, 3); my @path; print "@path\n" while @path = $i->();

Caution: Contents may have been coded under pressure.

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