I was doing this problem today:
https://brilliant.org/problems/its-easy-isnt-it/
First of all attempt the problem before proceeding further in this note. Got it? A lengthy solution?
Oh yes, I also figured it out after 30 mins (by solving cases). But this forced me to ponder that is there a short-and-sweet solution to this problem? Please tell me in the comments if you found one.
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Even I solved it by checking cases.......see the solution,....that also solves it the same way......But I don't see how you spent 30 minutes on this........maybe practicing enough questions will increase your speed.......:)
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30 mins was just a guess..
This is a very nice solution. As it turns out, each x in the absolute value will have maximum of 2 integer solutions. Since there are 3 x's in absolute value, there is 3 x 2 solutions: so 6 solutions is the complete total. I hope that was helpful, because this approach takes 15 seconds.
I've posted my approach.