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Red0's blog

I need math help
By Red0, history, 5 hours ago, In English

Today's mathforces contest screwed me over. Does anybody have good material suggestions so that I can quickly improve my skills in number theory and combinatorics?

Thanks!

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5 hours ago, # |
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Divisibility

Combinatorics

Bitwise operations

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    5 hours ago, # ^ |
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    Thanks! I'll check them out!

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5 hours ago, # |
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https://youkn0wwho.academy/topic-list

Use this.This has all the math topic that you'll ever require in cp. Just start with some common topics.There are quite high lvl topics also just skip them for now

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4 hours ago, # |
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Yeah I was shocked too I think cpalgorithms number theory section is great

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2 hours ago, # |
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I'm certainly not an expert but I am definitely better at math than coding for now. I don't think you needed a deep mathematical understanding to solve todays problems. For problem b for example, you just go, when does a light get changed? It has a divisor. For every divisor it as another number than goes with it right? (like 2 and 3 make 6). Does this mean every light stays on? Nah, when is the number of (unique) divisors not even. A perfect square. If you don't believe that a number has an odd num of divisors iff it is a perfect square. Try proving that an even number of divisors implies a number is not a perfect square, this is an equivalent statement in fact. After that the problem breaks down.

I'm by no means a great coder, in fact, I had a horrible contest because I didn't know the sqrt function was imprecise, which wasted me like 40 mins, but I hope what I said makes sense. Cheers!

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    86 minutes ago, # ^ |
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    Cheers brother :) I still can't understand why only perfect squares stay on though :/

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