11446 - Where is the 'back' button?

All about problems in Volume 114. If there is a thread about your problem, please use it. If not, create one with its number in the subject.

Moderator: Board moderators

sclo
Guru
Posts: 519
Joined: Mon Jan 23, 2006 10:45 pm
Location: Vancouver, BC, Canada
Contact:

Re: 11446 - Where is the 'back' button?

Post by sclo » Thu Apr 03, 2008 4:45 pm

Oh, no wonder I couldn't find any faster algorithm. I thought of a bruteforce O(n*2^n) algorithm long time ago, but thought that the time limit is too tight for it. Now I see that I can use bitmask to make it O(2^n), which should be fast enough.

baodog
Experienced poster
Posts: 202
Joined: Wed Jul 04, 2007 6:53 am

Re: 11446 - Where is the 'back' button?

Post by baodog » Thu Apr 10, 2008 4:14 am

Hi,

Nevermind...

Khaled_912
New poster
Posts: 33
Joined: Fri Jan 06, 2006 5:51 pm

Re: 11446 - Where is the 'back' button?

Post by Khaled_912 » Mon Apr 21, 2008 3:40 pm

We choose some leaves and make sure every node could reach at least one of them.
(and choose some roots to make sure every node could be reached from them)
I don't quite understand what you mean by this, can you elaborate more please?

Post Reply

Return to “Volume 114 (11400-11499)”