21–30 of 503 posts
He cheated more on writing a clickbait title than actually "cheating" on the interview. This is the same thing as when a kid in class thought studying was a way to cheat.
I would not have though to use this formula. The sum of the integers grows as the square of n so if n is anything but small you will overflow and get an erroneous answer. This interview question has everything bad imo: no practical uses, test knowledge of math formulas (which every math/CS major would have but none of the self learning folks). It’s very easy to stress and fail when given such a test, and even already…
> I would not have though to use this formula. The sum of the integers grows as the square of n so if n is anything but small you will overflow and get an erroneous answer. As long as you can get wraparound semantics, the overflow is actually unproblematic. (n(n+1)/2 + k) mod 2^32 - (n(n+1)/2 mod 2^32) = k mod 2^32 = k.
He cheated more on writing a clickbait title than actually "cheating" on the interview. This is the same thing as when a kid in class thought studying was a way to cheat.
It seems that knowing the famous anecdote about Gauss: https://www.americanscientist.org/article/gausss-day-of-reck... http://bit-player.org/wp-content/extras/gaussfiles/gauss-sni... would have helped as well.
I would not have though to use this formula. The sum of the integers grows as the square of n so if n is anything but small you will overflow and get an erroneous answer. This interview question has everything bad imo: no practical uses, test knowledge of math formulas (which every math/CS major would have but none of the self learning folks). It’s very easy to stress and fail when given such a test, and even already…
Yes, it's a question with a silly trick. Completely useless if one knows the answer, hard to spot if the person feigns struggle. Although, n•(n+1)/2 formula is not necessary. One can start with an xor sum and find the duplicate by xor adding elements again. This is another silly trick.
I would not have though to use this formula. The sum of the integers grows as the square of n so if n is anything but small you will overflow and get an erroneous answer. This interview question has everything bad imo: no practical uses, test knowledge of math formulas (which every math/CS major would have but none of the self learning folks). It’s very easy to stress and fail when given such a test, and even already…
> I would not have though to use this formula. The sum of the integers grows as the square of n so if n is anything but small you will overflow and get an erroneous answer. As long as you can get wraparound semantics, the overflow is actually unproblematic. (n(n+1)/2 + k) mod 2^32 - (n(n+1)/2 mod 2^32) = k mod 2^32 = k.
So actually not knowing the formula is kinda advantageous, because computing the sum as 1 + 2 + … + n (with every addition mod N) gives you the right answer (mod N).
I would not have though to use this formula. The sum of the integers grows as the square of n so if n is anything but small you will overflow and get an erroneous answer. This interview question has everything bad imo: no practical uses, test knowledge of math formulas (which every math/CS major would have but none of the self learning folks). It’s very easy to stress and fail when given such a test, and even already…
Yes, it's a question with a silly trick. Completely useless if one knows the answer, hard to spot if the person feigns struggle. Although, n•(n+1)/2 formula is not necessary. One can start with an xor sum and find the duplicate by xor adding elements again. This is another silly trick.
This would let the examiner fail a student for subjective reasons instead of academic success. The examiner would then be able to say « I failed them because of their skills, not because of their religions, look how easy the solution is ».
Perhaps this is what we are reproducing as an industry with all our convoluted interview processes, and it may be a decorum to choose the candidates we want instead of using objective criteria.
I would not have though to use this formula. The sum of the integers grows as the square of n so if n is anything but small you will overflow and get an erroneous answer. This interview question has everything bad imo: no practical uses, test knowledge of math formulas (which every math/CS major would have but none of the self learning folks). It’s very easy to stress and fail when given such a test, and even already…
I mean they might. Its a very famous formula, with a famous story attached, which is often covered in high school level math.
Regardless its a stupid question.
I would not have though to use this formula. The sum of the integers grows as the square of n so if n is anything but small you will overflow and get an erroneous answer. This interview question has everything bad imo: no practical uses, test knowledge of math formulas (which every math/CS major would have but none of the self learning folks). It’s very easy to stress and fail when given such a test, and even already…
Yes, it's a question with a silly trick. Completely useless if one knows the answer, hard to spot if the person feigns struggle. Although, n•(n+1)/2 formula is not necessary. One can start with an xor sum and find the duplicate by xor adding elements again. This is another silly trick.