Hacker Rank Week Of Code 31 notes

[this post is for my own use]

Week Of Code 31 beginning on 10th of April 2017

F# solutions to some of the problems: https://github.com/maglkp/weekofcode

Beautiful Word (E)
Simple sequence processing task.

Accurate Sorting (E)
Only slightly more challenging, for some reason got a timeout on the very last use case #10 for a minor point loss.

Zero-One Game (M)
Element removal game – winner computable in advance. A very interesting problem solvable in linear time removing all possible moves from sequence, required careful analysis of a lot of edge cases – failed to see two of them which cost me most of the points even though the rest was good, lesson learnt.

Spanning Tree Fraction (H)
Did some research but didn’t code this one, not a very wide known algorithm is seems but as often on HR it was possible to reduce it greatly analytically.

Colliding Circles (H)
Combinatorics / caching problem – I spent a lot of time devising an efficient memoization program but ultimately it was only able to solve 50% of the cases. An ingenious derivation proved it can be reduced to a trivial equation. Again this proves most of the harder challenges on HR are really maths / algorithmic problems, if you concentrate on programming side too much it means there is lots to improve in your math.

Nominating Group Leaders (E)
Split Plane (E)
Did not got to those – however they didn’t seem that much harder than the previous ones (which is preetty hard anyways :))