Hi all. I have an weighted graph for protien nodes. and I was writing a perl program to find the shortest path for a given node using the Dijkstra Algorithm. each protein(vertex) has equal weight. but my program doesn't stop iterating and doesn't give me an out put. I don't know which code is bringing me the error.

the idea is to accept the name of the protein node from the user and start searching the shortest path by taking the given protien as a root node.

thanks for helping me.

regards,

Michael Z.

sub dijkstra {  
        print "Enter a node\n";  
        my $root= <>;  
        my $infinity = "inf";  
        my %graph= %graph;  
        my %dist;  
        my %prev;  
        ############################ the algorithm ####  
        # first, set all distances to infinity  
        foreach $n (keys %graph) { $dist{$n} = $infinity; $prev{$n}=$n
+; }  
        # .. except the source  
        $dist{$root} = 0;  
        # loop while we have unsolved nodes  
        # sort unsolved by distance from root  
        foreach my $n1 (sort keys %graph) {  
            foreach my $n2 (keys %{$graph{$n1}}) {  
            if (($dist{$n2} eq $infinity) ||  
            ($dist{$n2} > ($dist{$n1} + $graph{$n1}{$n2}) )) {  
                $dist{$n2} = $dist{$n} + $graph{$n1}{$n2};  
                $prev{$n2} = $n1;  
                }  
            }  
        }  

        ##### print the solutions ######  
        my $path;  
        foreach $n(keys %graph) {   
            my $t = $n;  
            $path = $t;  
            while ($t ne $root) { $t = $prev{$t}; $path = "$t -> " . $
+path; }  
            print "$n\t$dist{$n}\t$path\n";  
        }  
    }  
    dijkstra();

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In reply to what is wrong with my Dijkstram algorithm? by Michael Z.

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