Educational Codeforces Round 63 (Rated for Div. 2)

Solutions for Educational Codeforces Round 63 (Rated for Div. 2) (contest 1155). 3/6 problems verified against sample I/O. Difficulty range: 1000-2800.

6 items

Educational Codeforces Round 63 (Rated for Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 3/6 | Rating range: 1000-2800 | Time: 11m 57s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Reverse a Substring	1000	implementation, sortings, strings	3m 29s	✗
B	Game with Telephone Numbers	1200	games, greedy, implementation	1m 27s	✓
C	Alarm Clocks Everywhere	1300	math, number-theory	1m 31s	✓
D	Beautiful Array	1900	brute-force, data-structures, divide-and-conquer	1m 43s	✓
E	Guess the Root	2200	brute-force, interactive, math	1m 39s	✗
F	Delivery Oligopoly	2800	brute-force, dp, graphs	2m 8s	✗

Practice › Codeforces Solutions › Educational Codeforces Round 63 (Rated for Div. 2) ›

CF 1155F - Delivery Oligopoly

We are given a simple undirected graph that is already 2-edge-connected. By Menger's theorem, this means every pair of vertices has two edge-disjoint paths between them, which is exactly the condition required by the two delivery companies.

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CF 1155A - Reverse a Substring

We are given a single string made of lowercase English letters. We are allowed to choose one contiguous segment inside this string and reverse that segment exactly once. After performing this single reversal, we obtain a new string.

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CF 1155D - Beautiful Array

We are given a sequence of integers and allowed to optionally pick exactly one contiguous segment and multiply every element inside it by a fixed value x.

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CF 1155E - Guess the Root

The problem gives us a hidden polynomial of degree at most 10 with integer coefficients, each strictly less than $10^6 + 3$. The task is to find an integer $x0$ such that the polynomial evaluates to zero modulo $10^6 + 3$.

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CF 1155C - Alarm Clocks Everywhere

We are given several event times, already sorted in increasing order. Ivan wants to configure an alarm clock that rings periodically. Once the first ring happens at minute y, the clock continues ringing at times: y, y + p, y + 2p, y + 3p, ...

Practice › Codeforces Solutions › Educational Codeforces Round 63 (Rated for Div. 2) ›

CF 1155B - Game with Telephone Numbers

We are given a digit string of odd length, and two players alternately delete single characters from it. The process continues until only 11 characters remain.