Disclaimer: This problem is from a contest on Hackerearth(hiring for intern) held on 13th April.

I was unable to solve this problem, can anyone help how to solve it? Can it be solved greedily or we need to use some graph algo?

Can someone recommend me problems on Dp from Project Euler Hackerrank.

I couldn't find much on googling it.

Thanks in advance.

Yesterday, I was stress testing the solution of problem E of some random participants from recent Div 3, with my solution but i couldn't hack them. After a few hours, two solutions which i stress tested got hacked but my stress testing couldn't catch where their solution was failing.
So, how do people find such a test cases to hack other's solution? Any suggestions are appreciated. Thank you.

Given an array and a value Sum, we need to print any three indices i, j, k such that i != j and j != k and arr[i] + arr[j] + arr[k] = Sum. Can we do it in better than N^2, something like NlogN?