# When? Question Answer
1 2 years, 7 months ago H - Queries with recurrences

How does array "A" change its values?

Operations of type 1 change the values of the array. The problem statement was modified to clarify this point.

2 2 years, 7 months ago E - Rotate circles

In this problem, the first test case is comparing 4 circles at the same time or is it comparing 2 and 2?

Two adjacent regions of EVERY pair of neighboring circles must have the same color.

3 2 years, 7 months ago D - Set

What does the last constraint stand for (the one that is about the total amount of elements in R)?

In case it is confusing:
"the total AMOUNT of elements in R" stands for
"the total NUMBER of elements in R".

4 2 years, 7 months ago D - Set

Is there more than one set that satisfies the conditions?

Any valid set will be Accepted.

5 2 years, 7 months ago I - Build me a fence

in problem I, the cordenates of points must be integer?


6 2 years, 7 months ago E - Rotate circles

Adjacency could be with circles in one column too?


7 2 years, 7 months ago D - Set

Can the set R have repeated elements?


8 2 years, 7 months ago B - String in the tree II

The only difference between problem A and problem B are in the constraints.

Don't look further!

9 2 years, 7 months ago General

Notice that in problems C (Chinese curves) and E (Rotate circles) colors of the images are relevant to understand the problem. If you have a black-and-white printed version, please see online version.


10 2 years, 7 months ago General

You can download PDF versions of the problems using the following links:



Good luck!