P is for Practical PerlMonks

### Re: (Golf) Shortest Graph Distance

by chipmunk (Parson)
 on May 12, 2001 at 00:15 UTC ( #79834=note: print w/replies, xml ) Need Help??

in reply to (Golf) Shortest Graph Distance

Here's a solution, which I'm fairly certain works as intended (but we saw where that got me last time ;)
```sub path {
(*g,\$f,\$t)=@_;@s=map[\$f,\$_,\$r{\$_}],keys%{*r=\$g{\$f}};
push@s,map[@p,\$_,\$d+\$r{\$_}],keys%{*r=\$g{\$n}}
while(@s=sort{\$b->[-1]<=>\$a->[-1]}@s),\$d=pop@{*p=pop@s},
(\$n=\$p[-1])ne\$t;@p
}
170 characters... Yikes! I'm sure someone can do better than that!

Update: Hey, I don't need to do that complicated initialization of @s!

```sub path {
(*g,\$f,\$t)=@_;@s=[\$f,0];
push@s,map[@p,\$_,\$d+\$r{\$_}],keys%{*r=\$g{\$n}}
while(@s=sort{\$b->[-1]<=>\$a->[-1]}@s),\$d=pop@{*p=pop@s},
(\$n=\$p[-1])ne\$t;@p
}
142 characters!

Update:

This solution will be very slow on the NYC to SF test case, because it gets stuck moving back and forth between Chicago, Cleveland, and Detroit for a while, because SF is so far away. However, it will find the solution eventually.

Of course, this could be fixed by preventing the code from moving back to a node that has already been visited, but we're optimizing for character count, not for speed of execution! ;)

Create A New User
Node Status?
node history
Node Type: note [id://79834]
help
Chatterbox?
 [Discipulus]: genial! one day I' also understand it.. ;=)

How do I use this? | Other CB clients
Other Users?
Others imbibing at the Monastery: (9)
As of 2018-03-23 19:40 GMT
Sections?
Information?
Find Nodes?
Leftovers?
Voting Booth?
When I think of a mole I think of:

Results (296 votes). Check out past polls.

Notices?