We will hold AAL Contest 001: Let's use segtree!, an official educational contest focused on segment trees, on AtCoder.

• Contest URL: https://atcoder.jp/contests/aalc001
• Start Time: https://www.timeanddate.com/worldclock/fixedtime.html?iso=20261012T1300&p1=248
• Duration: 300 minutes
• Number of Problems: 24
• Problem statements will be provided in both English and Japanese.
• This contest is unrated. There will be no rating updates.
• Writers: Nyaan, maspy
• Tester: Nachia

What Is the AAL Contest?

AtCoder offers AtCoder Algorithm Lectures, a series of courses explaining various theories and techniques used in competitive programming. Currently, the lectures are available only in Japanese, but we plan to offer an English version in the future.
In addition to courses in the form of explanatory articles and videos, AtCoder Algorithm Lectures will host AAL Contests as educational resources that allow participants to study specific topics in greater depth and gain practical experience.
We hope that you will use these contests to test your skills on the day of the contest and as learning materials afterward, together with the Algorithm Lectures courses.

This Contest's Topic

The topic of the first contest is segment trees.
Segment trees are known as one of the most frequently used data structures among those that are not built into programming languages. They can process aggregate queries in logarithmic time, and by carefully choosing the monoid they store, they can maintain many different kinds of information.
This contest features problems involving many different kinds of information stored in segment trees. Those who are not yet familiar with segment trees are encouraged to work through the problems and learn the techniques for designing the information maintained by a segment tree.
In addition, every problem in this contest can be solved using the segment tree or lazy segment tree provided by AtCoder Library. In other words, extended segment-tree data structures, such as persistent segment trees and Segment Tree Beats!, are outside the scope of this contest. Those who do not have their own segment tree library are encouraged to use the official library.
The problems from Problem R onward require not only knowledge but also substantial problem-solving insight. Advanced participants are also encouraged to take on the contest!

We are looking forward to your participation!