Codeforces Round 820 (Div. 3)

7 problems from Codeforces Round 820 (Div. 3) (contest 1729), difficulty 800-2100. 4/7 solutions verified against sample I/O.

7 items

Codeforces Round 820 (Div. 3)

Div. 3 | 7 problems | 4/7 verified | Difficulty 800-2100 | 34m 16s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Two Elevators	800	math	45,887	5m 44s	✓
B	Decode String	800	greedy, strings	32,472	6m 2s	✓
C	Jumping on Tiles	1100	constructive-algorithms, strings	21,640	6m 38s
D	Friends and the Restaurant	1200	greedy, sortings, two-pointers	30,717	3m 52s	✓
E	Guess the Cycle Size	1800	interactive, probabilities	7,915	6m 14s
F	Kirei and the Linear Function	1900	hashing, math	4,552	1m 48s	✓
G	Cut Substrings	2100	combinatorics, dp, hashing	2,507	3m 58s

Practice › Codeforces Solutions › Codeforces Round 820 (Div. 3) ›

CF 1729E - Guess the Cycle Size

We are interacting with a hidden structure that is guaranteed to be a simple cycle on $n$ vertices, where $n$ can be as large as $10^{18}$. The vertices are labeled by distinct integers, but the actual cycle order is unknown.

Practice › Codeforces Solutions › Codeforces Round 820 (Div. 3) ›

CF 1729G - Cut Substrings

We are given a text string and a pattern string. The operation allowed is to pick any occurrence of the pattern inside the text and replace that entire occurrence with dots. Those dots still occupy positions but no longer participate in further pattern matches.

Practice › Codeforces Solutions › Codeforces Round 820 (Div. 3) ›

CF 1729D - Friends and the Restaurant

We are given a collection of friends where each friend has two numbers: how much they intend to spend at a restaurant and how much money they actually have. The goal is to partition some of these friends into disjoint groups, where each group has at least two people.

Practice › Codeforces Solutions › Codeforces Round 820 (Div. 3) ›

CF 1729C - Jumping on Tiles

We are given a string of lowercase letters representing a line of tiles. Each position is a node in a path from the first character to the last, but we are not required to move only to adjacent positions.

Practice › Codeforces Solutions › Codeforces Round 820 (Div. 3) ›

CF 1729B - Decode String

We are given a string that was produced by encoding a lowercase English string character by character. Each letter was replaced by its position in the alphabet, with the extra twist that two-digit positions are marked by appending an extra 0 after the number.

Practice › Codeforces Solutions › Codeforces Round 820 (Div. 3) ›

CF 1729A - Two Elevators

The situation describes a decision between two elevators that can potentially reach Vlad on the 1st floor. Each elevator has a different movement rule, and the goal is to determine which one arrives back to floor 1 the fastest after Vlad presses a call button.

Practice › Codeforces Solutions › Codeforces Round 820 (Div. 3) ›

CF 1729F - Kirei and the Linear Function

We are given a digit string. For every query, we look at one substring of the original string, namely s[l..r], and compute its numeric value modulo 9. Separately, we may choose any two different substrings of fixed length w. Let their starting positions be L1 and L2.