### Matjaz's blog

By Matjaz, history, 7 years ago,

There are lots of problems on Codeforces — and most of them will never be seen by most users of the site.

Share a problem you think more people should know about!

(It can be because it's fun, educational, interesting or any other reason.)

• +51

 » 7 years ago, # |   +23 SpoilerIt uses a simple and really cool technique known as "+1 -1 trick". Do read the editorial to understand how to use it and how it works.
•  » » 3 weeks ago, # ^ |   0 thanks for this problem
•  » » 3 weeks ago, # ^ |   0 yupp! If you know about difference array then it's super easy
 » 7 years ago, # |   -6 733C SpoilerOne of the best greedy problems
•  » » 9 months ago, # ^ |   -8 Even the test cases were also visible and understandable. Thanks for the recommendation.
 » 7 years ago, # |   +8 P1, P2, P3, P4
 » 7 years ago, # |   +16 706E - Working routine SpoilerCan be solved using linked list like 2D structure.
•  » » 4 months ago, # ^ |   +3 What I love about this is that it can only be solved for a 2D matrix, and not if it was an array of size $10^5$.So in a sense, there is no easy 1D variant of the problem.
 » 7 years ago, # |   +3
 » 7 years ago, # | ← Rev. 3 →   -7 86D SpoilerMo's Algorithm, basic problem SpoilerDivide & Conquer DP optimization, basic problem SpoilerMo's Algorithm, medium problem
•  » » 7 years ago, # ^ |   +26 Dont post the hints openly that will spoil the party
•  » » » 7 years ago, # ^ | ← Rev. 2 →   0 Ah, OKUPD Edited.
 » 7 years ago, # |   +3 http://mirror.codeforces.com/contest/705/problem/C SpoilerUse a queue
 » 4 years ago, # | ← Rev. 2 →   +6 484D - Kindergarten SpoilerBecause I love this submission: Spoiler8757420
 » 4 years ago, # |   0
 » 9 months ago, # |   -8
 » 3 weeks ago, # |   -10 780B - The Meeting Place Cannot Be Changed SpoilerCool technique which will teach you how to deal with segments using binary search.