Codeforces Round 818 (Div. 2)

Solutions for Codeforces Round 818 (Div. 2) (contest 1717). 2/6 problems verified against sample I/O. Difficulty range: 800-2500.

6 items

Codeforces Round 818 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 2/6 | Rating range: 800-2500 | Time: 8m 9s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Madoka and Strange Thoughts	800	math, number-theory	57s	✓
B	Madoka and Underground Competitions	1100	constructive-algorithms, implementation	2m 1s	✗
C	Madoka and Formal Statement	1300	greedy	1m 39s	✗
D	Madoka and The Corruption Scheme	1900	combinatorics, constructive-algorithms, greedy	1m 2s	✗
E	Madoka and The Best University	2200	math, number-theory	1m 53s	✓
F	Madoka and The First Session	2500	constructive-algorithms, flows, graph-matchings	37s	✗

Practice › Codeforces Solutions › Codeforces Round 818 (Div. 2) ›

CF 1717E - Madoka and The Best University

We are asked to compute a sum over all triples of positive integers $(a, b, c)$ that sum to a given integer $n$. For each triple, we calculate the least common multiple of $c$ and the greatest common divisor of $a$ and $b$.

Practice › Codeforces Solutions › Codeforces Round 818 (Div. 2) ›

CF 1717F - Madoka and The First Session

We are asked to manipulate an array b of size n, initially all zeros, by performing a series of m operations defined by pairs of indices (vi, ui). For each pair, we choose one of two opposite operations: either decrease b[vi] by one and increase b[ui] by one, or the reverse.

Practice › Codeforces Solutions › Codeforces Round 818 (Div. 2) ›

CF 1717B - Madoka and Underground Competitions

We need to construct an n × n grid containing only '.' and 'X'. The grid must satisfy two conditions. First, every horizontal segment of length k must contain at least one 'X'. Second, every vertical segment of length k must also contain at least one 'X'.

Practice › Codeforces Solutions › Codeforces Round 818 (Div. 2) ›

CF 1717D - Madoka and The Corruption Scheme

We are asked to determine the smallest possible number of a winner in a single-elimination tournament with $2^n$ players. Each round halves the number of participants, and Madoka can choose both the initial pairing of players and the winner of each match.

Practice › Codeforces Solutions › Codeforces Round 818 (Div. 2) ›

CF 1717C - Madoka and Formal Statement

We are given two arrays of equal length. We start from the first array and are allowed to repeatedly increase individual elements by one.