Let's discuss problems.
How to solve the geography problem?
Let's discuss problems.
How to solve the geography problem?
Hey guys! Hello IOI 2018 contestants. How's everything at Japan?
Let's use this thread to get updates and discuss problems. Day 1 contest is a few hours away. Anyone who has a mirror link / live ranklist link please post in comments.
Hope everyone has a wonderful time!
We all have been waiting for this, a clean readable text version of Looking for a Challenge! My man Bar-B-Q informed me of it being finally out.
So without further adieu, here goes the link: https://www.nras.org.uk/data/events%20flyer%20front%20and%20back.pdf
Enjoy and leave a thanks for my man Bar-B-Q here. ^_^
Link: https://toph.co/p/breaking-math
The task is simple. Given n, k you gotta print
where ω(j) is the number of distinct prime factors of j.
Constraints: 1 ≤ k ≤ 10, 1 ≤ n ≤ 1011.
TL is fuckin' big, 15 seconds. Wut do?
Problem: 351E - Jeff and Permutation
Abridged statement: given n ≤ 2000 integers, we can multiply some of them by - 1. Goal is to minimize number of inversions (pairs (i, j) such that i < j and ai > aj). Print the minimum number of inversions.
Solution: 30244905
This solution replaces all numbers with its absolute value first. Then for each index i this solution adds min(L, R) to answer where L = number of smaller elements to left, R = number of smaller elements to right. Why does it work?
Why don't the IOI committee publish shortlisted problems and solutions like IMO does? It would be a great source of practice and countries could use the problems in their selection tests.