mahiro_zcy's blog

By mahiro_zcy, history, 6 hours ago, In English

One of my friends sent me this problem, and I don't know how to solve it.

I used bruteforce to solve cases with small $$$n$$$ and found that the answer is No when $$$n = 1$$$ or $$$n = 3$$$, otherwise the answer is Yes. But I don't know whether it is correct, and if it is correct, how to prove it?

Who can help me? Thank you.

The promblem statement is as follows.

Problem Statement
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5 hours ago, # |
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I think the idea is to classify the numbers based on their divisibility, and the first thing that stood out to me are the prime numbers, its pretty evident that you can only choose once for the prime numbers, and whichever you choose, Bob would choose 1, and then all the other primes would be lost.

Intuitionally speaking, Alice should always choose the biggest prime for the first step, then the biggest one divisible by 2 (until you can't), then the biggest one divisible by 3... and so on. Would be nice to find a certain mathematical proof for this but these are my thoughts for now

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    4 hours ago, # ^ |
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    Thanks, I will try to go deeper.