Art of Problem Solving: 2015 AMC 12 A #22

[@limbertpalomino9172]

When testing the "mods of 3 and 4", how did you get values ranging from 0 to 2? Were you adding, subtracting, dividing, multiplying?

[@jephayy]

+Limbert Palomino He added the previous 3 outcomes and took the mod 3 or 4 of that sum

[@someperson5137]

Mod n means the remainder when a number is divided by n. So m mod 3 would always be a number from 0 to 3

[@rome8432]

@@someperson5137 0-2 you mean

[@jharnamandal2855]

Too nice. Can you make videos on the different strategies on how to approach a particular set of problems of similar type?

[@prathikkannan3324]

AMC problem you can’t solve without knowledge of recursion seems kind of unfair.

[@someperson5137]

Dang, my solution was way too complicated. My recursion was S(n)=S(n-2)+2S(n-3)+3S(n-4)+2S(n-5)+S(n-6). Took me about an hour to figure it out. At least I got the right answer tho

[@someperson5137]

Lol, I checked my sequence against his and realized I was wrong

[@tomyao7884]

I think that the solution is brilliant, but I think it could be explained more clearly. I had to pause the video many times to figure out what you were trying to say. Or maybe it's just that i'm dumb. ^_^

[@rajpanchal9226]

looks like i'm dumb as well

[@rajpanchal9226]

or we both are new to these techniques.

[@worldhello3736]

Me too lol . I had to go back and forth to really understand it

[@edmunds4635]

Tom Yao me2 not really sure what the fuck happened

[@mr.orca3251]

that problem is just super hard, tbh I'm kinda glad that i looked it up since i would have spent at least another 5 months thinking about it

[@barinderjassalsingh5210]

I live in India and it's impossible to buy books by AOPS since they are very costly to me plz upload a link to download

[@rishidesai9755]

+Bainder jassal Singh Downloading is illegal. Amazon has the books for cheaper prices, second hand.

[@polychats5990]

I always get mixed up with the directions. I thought that for example, the sequence AAA would not work because it has three A's in a row. If this is assumed the answer is much more simple.

[@jurius2124]

nice explanation^

[@Itsdaquenchiest]

Faurkkk too good

[@jimpim6454]

Yikes!

[@jurius2124]

nice explanation^