FAQs

Oh, I did not know that. The CS committee in my country uses dropbox often, so I figured it is quite good. But hearing this, I will start using Pastebin.

Thanks for the information. I really didn't know. I seek to constantly evolve....

@Prasun Biswas if the file is lesser than 20MB are there any problems with downloading via dropbox? The thing is, dropbox is quite handy, for me at least, and if I can use it for smaller files, I would do so.

In file called "AinA.txt", an array is given. The array is described in the following manner: First, a number is given, and it represents how many elements the array has. That is $10^5$. The following $10^5$ numbers are elements of that array. Now, it is asked to find how many special sub-arrays exist in the given array. Those special sub-arrays have two properties/characteristics. First one, they have to have at least 2 elements. Second one, the first number and the last one of the sub-array have to be the same number. One more example:

Array has 4 elements: 1 2 2 3

Here we have 4 sub-arrays that have exactly one element {1} , {2}, {2} and {3}, but since they have only one element, they aren't qualified.

Next, we have 3 sub-arrays with exactly 2 elements in it, those are: {1, 2}, {2, 2} and {2, 3}. From these, only {2, 2} satisfies both properties, so: one qualified sub-array for now.

With 3 elements, there are 2 sub-arrays: {1, 2, 2} and {2, 2, 3}. Here, both sub-arrays do not satisfy the second property (first and last the same).

Lastly, there is one sub-array with for elements, and it is the actual starting array {1, 2, 2, 3} and he does not satisfy the second condition either.

Conclusion: There is only one special sub-array (and it is {2, 2}) in the initially given array ( {1, 2, 2, 3} ). So the answer for this example is $\boxed{1}$. I hope I managed to explain it to some extent and I do apologise for my late response and any other unconviniences, I am in a bit of a haste, and away from home. Good luck :)

Thank you kindly for the encouragement! I am glad to hear so. I will try to come up with prospectively exciting and fun problem in the future. All the best.

Depends on my mood and the time of the day.

No special reason to be honest. I just pick the one randomly, .in .dat .bin or with no extension. Probably there is some difference between them, but with my knowledge, I cannot tell for sure.

Yeah I agree, and 29MB is a bit too much!!

I understand. I thought that especially this may represent a problem, but I haven't provided better explanation for some reason. I will add a better explanation what the $S$ actually is in the problem, but I will explain it here as well.

The standard EOTR has a rectangle $ABCD$ for its base and points $P$ and $Q$ for its "main peak points", so that the $PQ$ is so called "peak line". It is said that the length of the following segments: AP, DP, BQ and CQ must be the same. That length is labelled as that $S$. So, it means that $AP = DP = BQ = CQ = 5\sqrt{6}$. I edited some minor text in the problem, would You mind checking it out and informing me whether it is more understandable now? :)

Thank You for pointing this out. If you have any more questions, use this FAQ note again. :)

Best regards

Two numbers are given: $m$ and $n$. $n$ says that number of elements of the array in the problem is exactly $n$, while $m$ says that elements of the array are positive integers lesser or equal to $m$. Another important thing is that the array must be strictly increasing. Example (in the case I did not cover everything):

n = 2, m = 3: Array = $a_1$, $a_2$ ; and the the possible values for elements are from set {1, 2, 3}. For this trivial example, answer is $\boxed{3}$ and those arrays are:

• $A_1 = 1, 2$
• $A_2 = 2, 3$
• $A_3 = 1, 3$

Do you think that I should perhaps provide example for the problem (within the problem itself)?

Not really : /