Thursday, March 30, 2006
wow... its only the 5th post? cool... but i know one which stopped at one, so we're not that bad... so far... only two of us have blogged, though all of us have tagged except Joy... ok. so after my totally unlogical [inlogical? illogical?] observation... i will start blogging what i came here to blog about... which is apparently... ohman... i forgot... haii... nevermind... i shall do here what i did in my class blog to make it undeaded [not a word... but i dont care.] so... ya... brainteasers... this one is about something that we all know about, but never bothered to do...
A computer science teacher poses his students a problem.
"I want you write a computer program that plays tic-tac-toe legally and runs through ALL the possible combinations of the game, and finds out the total."
The students settle down to work..
An hour later, a student gets up and proclaims "I've got it! The number of possible combinations in a game is 344,242."
At which point another student quickly replies, "I haven't finished yet, but I'm sure Fred made a mistake in his program."
Why?
think about it... and DONT SCROLL DOWN till you give up...
hey i told you not to scroll down... think id post the answers within the same post? SO WRONG!!! MUAHAHAHAHAHAHAHA
ok im bored to death, so heres the answer:
The total combinations can be partitioned into first move groups. Positions starting at corners and sides are indistinguishable. This means that each ofthem (4) must yield the same number of combinations.
Total = 4*(Corner) + 4*(Side) + Middle
In Middle games, the second move is inevitably a corner or side. Because the middle mark is in the middle, symmetry still applies, as in the previous calculation.
T = 4C + 4S + (4C' + 4S')T = 4(C + S + C' + S')
The number given by the first student is not divisible by 4. So even though the second student does not know the exact value, he knows fred´s suggestion is incorrect.
Dont mess with US!!
5:45 PM
