Hi Everyone,

I gave my first ever contest on codeforces recently which was Codeforces Educational Round 151 and I am really happy to become rated. The problems felt really good, I was able to solve A,B and C during the contest and later I was able to upsolve D. I also placed 2530. Since this was my first contest here I would like to make it special by thanking the creators of this round namely adedalic , BledDest , Neon and awoo with all my heart via this blog. Thank you so much guys, keep up the good work !

The problem statement can be referred from here. In short you are given an array "prices" and you need to determine the maximum profit one can earn by doing atmost k trades. You cannot buy a stock unless you have sold the previous one. The dynamic programming solution to this is well known and solves the problem in O(nk) time but did you know a stack+heap solution to this also exists that solves the problem in O(n+nlogk) time? This second solution is not as famous and I have only ever managed to find 2 or 3 articles explaining the solution and that too were not very clear and full of symbols instead of a visual explanation. So here in this article I will try to explain this solution as clearly as I can.