Welcome to BrainDen.com - Brain Teasers Forum
|Welcome to BrainDen.com - Brain Teasers Forum. Like most online communities you must register to post in our community, but don't worry this is a simple free process. To be a part of BrainDen Forums you may create a new account or sign in if you already have an account.
As a member you could start new topics, reply to others, subscribe to topics/forums to get automatic updates, get your own profile and make new friends.
Of course, you can also enjoy our collection of amazing optical illusions and cool math games.
If you like our site, you may support us by simply clicking Google "+1" or Facebook "Like" buttons at the top.
If you have a website, we would appreciate a little link to BrainDen.
Thanks and enjoy the Den :-)
A Child and a Staircase
Posted 21 June 2012 - 05:21 PM
Posted 22 June 2012 - 01:38 AM
Since we can solve this with either Fibonacii numbers or combinations, we can conclude that
F10 = C(10,0) + C(9.1)+ ...+c(5.5).
More generally Fn = C(n,0) + C(n-1.1) + C(n-2,2) + ... as long as the first number is no les than the second.
NOTE If you interpet the question to mean 10 steps plus the upper landing the answer would be F11, a point one poster raised. In addition if we distinquish between first strride right foot and first stride left we would double our answer.
Posted 22 June 2012 - 04:56 AM
Vidi vici veni.
Posted 22 June 2012 - 05:36 AM
Posted 06 January 2013 - 05:27 PM
I think 89 is correct. Here's a simple C# implementation that you can test out if you want to use LinqPad:
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users