Bracket Sequence
A bracket sequence is a string, containing only characters “(“, “)”, “[” and “]”. A correct bracket sequence is a bracket sequence that can be transformed into a correct […]
Month: May 2020
Dice Tower
A dice is a cube, its faces contain distinct integers from 1 to 6 as black points. The sum of numbers at the opposite dice […]
Unsolvable
Consider the following equation:where sign [a] represents the integer part of number a. Let’s find all integer z (z > 0), for which this equation is unsolvable in positive integers. The phrase “unsolvable in […]
Well-known Numbers
Numbers k-bonacci ( k is integer, k > 1) are a generalization of Fibonacci numbers and are determined as follows: F(k, n) = 0, for integer n, 1 ≤ n < k; F(k, k) = 1; F(k, n) = F(k, n - 1) + F(k, n - 2) + … + F(k, n - k), for integer n, n > k. Note that we determine […]
Fence Planks
John Doe has a crooked fence, consisting of n rectangular planks, lined up from the left to the right: the plank that goes i-th (1 ≤ i ≤ n) (from left to right) has […]
Merging Two Decks
There are two decks of cards lying on the table in front of you, some cards in these decks lay face up, some of them […]
Road Repairs
A country named Berland has n cities. They are numbered with integers from 1 to n. City with index 1 is the capital of the country. Some pairs of cities have monodirectional […]
LCM Challenge
Some days ago, I learned the concept of LCM (least common multiple). I’ve played with it for several times and I want to make a […]
Let’s Play Osu!
You’re playing a game called Osu! Here’s a simplified version of it. There are n clicks in a game. For each click there are two outcomes: correct […]
Old Peykan
There are n cities in the country where the Old Peykan lives. These cities are located on a straight line, we’ll denote them from left to right […]
Mirror Box
Mirror Box is a name of a popular game in the Iranian National Amusement Park (INAP). There is a wooden box, 105 cm long and 100 cm high in […]
Challenging Balloons
Martha — as a professional problemsetter — proposed a problem for a world-class contest. This is the problem statement: Tomorrow is Nadia’s birthday, and Bardia […]
