Codeforces Round 940 (Div. 2) and CodeCraft-23

7 problems from Codeforces Round 940 (Div. 2) and CodeCraft-23 (contest 1957), difficulty 800-2700. 1/7 solutions verified against sample I/O.

7 items

Codeforces Round 940 (Div. 2) and CodeCraft-23

Div. 2 | 7 problems | 1/7 verified | Difficulty 800-2700 | 12m 56s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Stickogon	800	constructive-algorithms, greedy	25,669	43s	✓
B	A BIT of a Construction	1100	bitmasks, constructive-algorithms, greedy	20,399	1m 56s
C	How Does the Rook Move?	1600	combinatorics, dp, math	11,932	1m 54s
D	A BIT of an Inequality	1900	bitmasks, brute-force, dp	5,810	2m 7s
E	Carousel of Combinations	2400	brute-force, combinatorics, dp	1,623	2m 15s
F1	Frequency Mismatch (Easy Version)	2600	binary-search, data-structures, divide-and-conquer	664	2m 8s
F2	Frequency Mismatch (Hard Version)	2700	binary-search, data-structures, dfs-and-similar	610	1m 53s

Practice › Codeforces Solutions › Codeforces Round 940 (Div. 2) and CodeCraft-23 ›

CF 1957E - Carousel of Combinations

We are counting circular arrangements of selected elements, then mixing that count with a modular reduction that depends on the size of the selection.

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CF 1957F1 - Frequency Mismatch (Easy Version)

We are working on a rooted tree where each node carries a small integer label. Each query gives us two paths in the tree. For each path, we can think of walking from one endpoint to the other and collecting the multiset of node values along the way.

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CF 1957F2 - Frequency Mismatch (Hard Version)

We are given a tree with $n$ nodes, each node labeled with an integer value. The tree is unrooted, but conceptually we can root it anywhere for processing. For each query, we are asked to compare the multiset of values along two paths in the tree.

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CF 1957D - A BIT of an Inequality

We are given an array of integers and asked to count all triples of indices $(x, y, z)$ where $1 le x le y le z le n$, such that the XOR of two subarrays, $f(x, y)$ and $f(y, z)$, is strictly greater than the XOR of the entire range from $x$ to $z$, denoted $f(x, z)$.

Practice › Codeforces Solutions › Codeforces Round 940 (Div. 2) and CodeCraft-23 ›

CF 1957B - A BIT of a Construction

We are asked to build an array of length n consisting of non-negative integers whose total sum is exactly k. Among all such arrays, we want to maximize the number of set bits in the bitwise OR of all elements.

Practice › Codeforces Solutions › Codeforces Round 940 (Div. 2) and CodeCraft-23 ›

CF 1957C - How Does the Rook Move?

We are playing a two-player game on an $n times n$ chessboard. You place a white rook on your turn and the computer places a black rook immediately after, mirroring your move across the main diagonal, meaning the rook at $(r, c)$ is mirrored to $(c, r)$.

Practice › Codeforces Solutions › Codeforces Round 940 (Div. 2) and CodeCraft-23 ›

CF 1957A - Stickogon

We are given a collection of sticks, each with an integer length. The goal is to build as many regular polygons as possible using these sticks, with the restriction that each side of a polygon must be exactly one stick, and no stick can be reused.