Discussion @ 1677. Monkey at the Keyboard @ Timus Online Judge

task is improper allaksus 9 Mar 2009 08:45

I cannot understand how much probability.
If probability equal 1, answer in infinity.

Edited by author 09.03.2009 09:02

Re: task is improper Al.Cash 9 Mar 2009 16:25

You don't have the right to call the problem improper only because you don't understand it!!!
Maybe read the statement more carefully and find out what is the expected time in mathematics.

Re: task is improper allaksus 13 Mar 2009 20:36

I think I understend task well and how decide it if we don't think about probability. If we have {2,"ba"} I find the solve is 4.6(6). But monkey can push "bbbbbb" with probability>0. You can answer me to allaksus@rambler.ru .

Re: task is improper Al.Cash 13 Mar 2009 21:12

Actually the probability of typing "bbbbbb..." (infinity times) is 0 although this can happen!
And the answer to {2,"ba"} is exactly 4.

Re: task is improper allaksus 13 Mar 2009 22:49

Sorry, I agree with you =4 (I found one error), but the probability this event is 0.6875 . Why it isn't 0.999 or 0.99999.

Re: task is improper allaksus 13 Mar 2009 23:24

If I will be audietorium I will be intrest how many maximum time I must wait with probability 0.99

Re: task is improper Al.Cash 14 Mar 2009 00:47

You mustn't find the maximum time but the EXPECTED time, which is equal to 1*P(1) + 2*P(2) + 3*P(3) + 4*P(4) + ...
P(i) is the probability of the situation, where the first appearance of the required word ends at position i.
I don't know how to explain it more clearly.

No subject Al.Cash 14 Mar 2009 00:47

Edited by author 14.03.2009 01:42

Re: No subject allaksus 14 Mar 2009 12:18

The task doesn't say about condition (EXPECTED time, maximum time, ...) .

Discussion of Problem 1677. Monkey at the Keyboard