Codeforces Round 896 (Div. 2)

Solutions for Codeforces Round 896 (Div. 2) (contest 1869). 2/7 problems verified against sample I/O. Difficulty range: 900-3000.

7 items

Codeforces Round 896 (Div. 2)

Type: Div. 2 | Problems: 7 | Verified: 2/7 | Rating range: 900-3000 | Time: 12m 13s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Make It Zero	900	constructive-algorithms	2m 38s	✗
B	2D Traveling	1100	geometry, math, shortest-paths	1m 32s	✓
C	Fill in the Matrix	1300	constructive-algorithms, math	1m 38s	✗
D1	Candy Party (Easy Version)	1700	bitmasks, constructive-algorithms, graphs	1m 28s	✓
D2	Candy Party (Hard Version)	2100	bitmasks, constructive-algorithms, dp	1m 35s	✗
E	Travel Plan	2400	combinatorics, dp, math	2m 19s	✗
F	Flower-like Pseudotree	3000	constructive-algorithms, graphs, greedy	1m 3s	✗

Practice › Codeforces Solutions › Codeforces Round 896 (Div. 2) ›

CF 1869E - Travel Plan

We are asked to consider a country with $n$ cities connected in a tree-like structure that mirrors a complete binary tree. Each city $i$ has edges to $2i$ and $2i+1$ if those indices do not exceed $n$.

Practice › Codeforces Solutions › Codeforces Round 896 (Div. 2) ›

CF 1869F - Flower-like Pseudotree

This problem is a Codeforces 3000-rated constructive graph problem. Producing a correct editorial requires reconstructing and proving the entire degree-sequence characterization of flower-like pseudotrees, together with the linear-time construction used in the official solution.

Practice › Codeforces Solutions › Codeforces Round 896 (Div. 2) ›

CF 1869D2 - Candy Party (Hard Version)

We have a party with n people, each bringing a certain number of candies. Each person can give exactly a power-of-two number of candies to another person, and every person can give to at most one person and receive from at most one person.

Practice › Codeforces Solutions › Codeforces Round 896 (Div. 2) ›

CF 1869A - Make It Zero

For Codeforces 1869A, the entire solution is a constructive observation. If n is even, perform: After the first operation, every element becomes X, where X is the XOR of the whole array.

Practice › Codeforces Solutions › Codeforces Round 896 (Div. 2) ›

CF 1869C - Fill in the Matrix

We are asked to construct an $n times m$ matrix where every row is a permutation of the numbers from $0$ to $m-1$. This means each row contains all values exactly once, but rows can differ from each other. Once the matrix is built, each column induces a multiset of $n$ values.

Practice › Codeforces Solutions › Codeforces Round 896 (Div. 2) ›

CF 1869D1 - Candy Party (Easy Version)

We have a party with n people, each holding a certain number of candies ai. Each person will give a positive number of candies to exactly one other person, and each person will receive candies from exactly one other person.

Practice › Codeforces Solutions › Codeforces Round 896 (Div. 2) ›

CF 1869B - 2D Traveling

We are given several test cases, each describing a complete weighted travel system on a plane. Every city is a point with integer coordinates, and we are allowed to fly directly between any pair of cities.