xuanity's blog

By xuanity, history, 4 months ago, In English

Hi guys,

So I was just doing some good old questions around the problemset, i started doing the difficulty of 800 questions, and i came up to this old question which was created from the beta days of codeforces

The question I faced is this: Codeforces Beta Round 9, Problem A

9A: Die Roll

So the question in short stated that Dot is going to throw a dice(die), if the points of the dice(die) thrown by Dot is higher than Yakko and Wakko, she will win, so what is the probability of Dot winning (Maybe i misunderstood or something)

https://mirror.codeforces.com/problemset/problem/9/A

and a key point the question stated is: It is known that Yakko and Wakko are true gentlemen, that's why if they have the same amount of points with Dot, they will let Dot win.

So when i take a look at the test case 1, we know that Yakko got 4 and Wakko got 2. So Dot needs 5,6 to win. But since being tied with Yakko or Wakko will also let Dot win because they are gentlemen, therefore we must also include the 4 and 2 to the probability of Dot winning. That makes it 2,4,5,6 to win for Dot. But why does the answer provided is 1/2 which is 3/6, while the correct answer is 4/6 or (2/3) cuz there are 4 numbers that makes Dot win.

Anyone can help solving my problem, Thanks Guys

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