摘要:
C. Place for a Selfie The universe is a coordinate plane. There are $n$ space highways, each of which is a straight line $y=kx$ passing through the or 阅读全文
摘要:
D. A Wide, Wide Graph You are given a tree (a connected graph without cycles) with $n$ vertices. Consider a fixed integer $k$. Then, the graph $G_k$ i 阅读全文
摘要:
C. Candy Store The store sells $n$ types of candies with numbers from $1$ to $n$. One candy of type $i$ costs $b_i$ coins. In total, there are $a_i$ c 阅读全文
摘要:
D. Binary String Sorting You are given a binary string $s$ consisting of only characters 0 and/or 1. You can perform several operations on this string 阅读全文