### giorgosgiapis's blog

By giorgosgiapis, history, 2 months ago,

Perhaps this is an unpopular opinion but I think we need more testers that are on the lower side of the rating spectrum. Having only red/orange testers for Div 2 contests might (and does) result in underestimation of the difficulty of the proposed problems. Blue/cyan or even green/gray form a more representative sample for the actual contestants. I understand that there should be a few highly rated and experienced testers but having only them can result in speedforces rounds for Div 2 participants.

• +162

By giorgosgiapis, history, 3 months ago,

Round 1B of the Google CodeJam contest just finished. What are your thoughts/comments on this round? I found the problems to be a bit unbalanced in difficulty which resulted in a lot of ties.

• +58

By giorgosgiapis, history, 4 years ago,

The PEG Wiki (http://wcipeg.com/wiki) is down for quite some time now although the main site (https://wcipeg.com/main) seems to be working fine. Does anybody know what happened to it? Is this something permanent? The wiki had some excellent articles which shouldn't be lost.

• +17

By giorgosgiapis, history, 4 years ago,

So I came up with this problem yesterday, which I couldn't solve. With a quick google search I found nothing relevant so I thought I could ask here for help.

### The Problem

You are given a tree T with n nodes and an integer k. You are asked to find the length of longest path in T which has exactly k inversions. Here we define path inversions for a specific path P as the number of inversions in the array of the nodes visited in P, in that order. If there is no such path output  - 1.

Let's consider the above tree for example, with k = 2. The answer is 4 since the path 1 - 6 - 2 - 5 has exactly 2 inversions. Note that the path 5 - 2 - 4 also has 2 inversion however it isn't the path with the maximum length.

I am looking for solutions with complexity better than O(n2·logn)

• +8

By giorgosgiapis, history, 5 years ago,

Sixth round of COCI 2017/2018 season will take place this Saturday at 14:00 UTC.
You can find the full schedule for this season here and register for the contest here.

Let's discuss the problems here after the contest.

• +28

By giorgosgiapis, 5 years ago,

Fourth round of COCI 2017/2018 season will take place this Saturday at 14:00 UTC.
You can find the full schedule for this season here and register for the contest here.

Let's discuss the problems here after the contest.

• +31

By giorgosgiapis, 5 years ago,

Third round of COCI 2017/2018 season will take place this Saturday at 14:00 UTC.
You can find the full schedule for this season here and register for the contest here.

Let's discuss the problems here after the contest.

• +29

By giorgosgiapis, 5 years ago,

Second round of COCI 2017/2018 season will take place this Saturday at 14:00 UTC.
You can find the full schedule for this season here and register for the contest here.

Let's discuss the problems here after the contest.

• +41

By giorgosgiapis, 5 years ago,

First round of this year's COCI will take place today at 14:00 UTC.
You can find the full schedule for this season here and register for the contest here.

Let's discuss the problems here after the contest.