The Programming Blog

Hackathons are always awesome !! You build a product, interact with other hackers and overdose yourself off caffeine. And if we get unlimited RedBull, then it's just 10X Awesomeness.

My team was selected into the finals of Smart India Hackathon. We were selected for the Indian Space Research Organisation category.

Problem Statement: Novel Solution for preventing a breach of the confidential file from the organization other than already available methods in networking. The solution should also prevent uploading of data to the internet.

Solution: Our idea for this was a client-side solution: On every employee system, we will partition the system volume into two parts: Public and Confidential. Public Volume contains all the data that can go outside organization without any concern. Confidential Area contains all the confidential data deployed by system admin into this volume.

The Confidential Area will be completely isolated i.e. None of the following can be done on files of this area: Cut, Copy, Send To, Save As, Paste, Delete, Drag and Drop and many more commands. This ensures that none of the files from the confidential area can move to the public area or external drives.

What about uploading to Internet/Mail/Backend Script ?? How can we stop this ??

Our solution to this problem was: When the user wants to open confidential area, the user has to use our File Viewer tool to open the files.
At all other times, all the permission on file of the Confidential area will be revoked. This means that if the user tries to upload a file, it will be corrupt. The user may try bash script, program or any other way, it will not work because file simply does not exist without permissions.

File permissions will only be granted when the user opens the confidential file in File Viewer. Also, during this time (when File Viewer is opened), we are checking that FileViewer is in focus. Because the user can open File Viewer and then take advantage of granted file permissions.

We also handled a lot of other edge cases and were able to develop 60% of our product (Isolation part was done completely using a combination of registry modification, clipboard listeners to clear clipboard when copied data comes in, etc).

The further product development will be carried on after instructions from Indian Space Research Organisation.

This was my first Hackathon. And I bet, more are coming.

Many times Android Studio just wouldn't work. You will see some weird errors while building and stackoverflow will also fail you on this.

Its 4.30 in the night (or just call it morning) and here I am discussing interesting issue I came across in PowerUp Game a couple of days back.

Winning the 4th Edition of Discover Thinking Contest by CSI

Yesterday, I and my two friends participated in a competitive programming challenge on Hackerearth. It was tiring for us as the place we decided to meet was occupied and we had to change places while the competition was running. Also, we had to rely on mobile internet which unfortunately is not so good.

So, now lets see how to know the Big-oh complexity for a given competitive programming questions.So follow this approach -

1.In all the platforms, you will be given a time limit in seconds according to the language you choose.Some platforms may not give you time limit for your programming language directly ,so calculate it as-

a. Codechef - codechef calculation -So,as said in the article multiply your language multiplier given here with the time limit given in the problem.

Ex- If time limit given in the problem is 2 sec ,then for Java  multiplier is 2X,thus

time limit for Java = 4 sec

b. For hackerrank, refer this-Hackerrank Time

Similarly you can see by yourself to get the time limit for your language.We will calculate for C++.Thus for C++,its mostly 2 sec /given in problem  (multiplier is 1 ,s no problem).

2.Now you need to calculate the no. of operations your programming language can compute in 1 sec.
So for C/C++ its usually around 10^8 operations per sec.
Similarly you can see for other languages.

3.Once you have got the time limit for your programming language ,now you need to calculate the total no. of operations for the given problem.For ex-

a.If  n is test case limit and m is input limit then ,worst case no. of operations performed will be-
m*n.

so if m*n =N

So, for a 1sec time limit, (keeping 10^8 operations per sec in mind)

N>10^8: better than O(N), maybe O(nlogn)
N=10^6-10^7 : O(n) solution is required.
N=10^5 : O(nlogn) solution.
N=10^4 : O(n^1.5 or n(logn)^2) solution.
N=10^3 : O(n^2) solution.
N=10^2 :O(n^3) solution.
N=10:O(n!) and O(2^n)  solution.

Above will be valid for java if time limit is 2 sec.But in all platform time limit is given wrt C++.So,just look at the above always.

For ex, let say you want to know above template for java on hackerrank.So,on hackerrank java is 4 sec ,but anyway we will look at C++.For C++, its 2 sec.

which means,template is-
N>2 X 10^8: better than O(N), maybe O(nlogn)
N=2 X 10^6-10^7 : O(n) solution is required.
N=2 X 10^5 : O(nlogn) solution.
N=2 X 10^4 : O(n^1.5 or n(logn)^2) solution.
N=2 X 10^3 : O(n^2) solution.
N=2 X 10^2 :O(n^3) solution.
N=2 X 10:O(n!) and O(2^n)  solution.