Codeforces Round 878 (Div. 3)

Solutions for Codeforces Round 878 (Div. 3) (contest 1840). 4/8 problems verified against sample I/O. Difficulty range: 800-2500.

8 items

Codeforces Round 878 (Div. 3)

Type: Div. 3 | Problems: 8 | Verified: 4/8 | Rating range: 800-2500 | Time: 13m 11s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Cipher Shifer	800	implementation, strings, two-pointers	1m 10s	✗
B	Binary Cafe	1100	bitmasks, combinatorics, math	1m 8s	✓
C	Ski Resort	1000	combinatorics, math, two-pointers	1m 11s	✓
D	Wooden Toy Festival	1400	binary-search, greedy, sortings	1m 41s	✓
E	Character Blocking	1600	data-structures, hashing, implementation	3m 6s	✗
F	Railguns	2200	brute-force, dfs-and-similar, dp	1m 54s	✓
G1	In Search of Truth (Easy Version)	2200	constructive-algorithms, interactive, math	1m 40s	✗
G2	In Search of Truth (Hard Version)	2500	constructive-algorithms, interactive, math	1m 21s	✗

Practice › Codeforces Solutions › Codeforces Round 878 (Div. 3) ›

CF 1840G1 - In Search of Truth (Easy Version)

We are given a circular arrangement of sectors numbered from 1 to some unknown integer $n$. The sectors are arranged in a fixed, but arbitrary order, and we initially see the number of the sector where the arrow points.

Practice › Codeforces Solutions › Codeforces Round 878 (Div. 3) ›

CF 1840G2 - In Search of Truth (Hard Version)

We are placed in a circular arrangement of sectors numbered from 1 to $n$, but we do not know either the total number $n$ or the order of the numbers around the circle. Initially, the arrow points to a sector, and we are told its number.

Practice › Codeforces Solutions › Codeforces Round 878 (Div. 3) ›

CF 1840E - Character Blocking

Thanks for providing the input/output. From the symptoms, the actual bug is clear: the previous solution was just summing ASCII values of characters in the string (ord(c)), which produces numbers like 529 or 670. The expected outputs (11088, 10010, etc.

Practice › Codeforces Solutions › Codeforces Round 878 (Div. 3) ›

CF 1840F - Railguns

We move on a grid of coordinates from (0, 0) to (n, m). Every second we may increase the first coordinate by one, increase the second coordinate by one, or stay where we are. The position after the action is the position checked against all railgun shots fired at that second.

Practice › Codeforces Solutions › Codeforces Round 878 (Div. 3) ›

CF 1840D - Wooden Toy Festival

We have a small workshop with three wood carvers and a list of people who will request toys. Each toy request is represented by an integer pattern. Each carver can pre-learn one pattern perfectly.

Practice › Codeforces Solutions › Codeforces Round 878 (Div. 3) ›

CF 1840C - Ski Resort

The problem asks us to count how many ways Dima can choose consecutive vacation days at a ski resort given weather constraints.

Practice › Codeforces Solutions › Codeforces Round 878 (Div. 3) ›

CF 1840A - Cipher Shifer

The proposed solution does not attempt to address the exercise at all. Exercise 3.3.1.16 asks for an asymptotic analysis of the normalized incomplete gamma function for large $x$ and then its application to approximating $t$ in a cumulative chi-square relation.

Practice › Codeforces Solutions › Codeforces Round 878 (Div. 3) ›

CF 1840B - Binary Cafe

We are asked to count the number of ways Toma can select desserts in a binary-themed cafe. Each dessert has a cost that is a power of two: the first dessert costs 1 coin, the second 2 coins, the third 4 coins, and so on, following the sequence $2^0, 2^1, 2^2, dots, 2^{k-1}$.