Codeforces Round 863 (Div. 3)

Solutions for Codeforces Round 863 (Div. 3) (contest 1811). 4/8 problems verified against sample I/O. Difficulty range: 800-2200.

8 items

Codeforces Round 863 (Div. 3)

Type: Div. 3 | Problems: 8 | Verified: 4/8 | Rating range: 800-2200 | Time: 16m 1s

Problem Name Rating Tags Solve Time Verified
A Insert Digit 800 greedy, math, strings 1m 31s ✓
B Conveyor Belts 1000 implementation, math 1m 40s ✓
C Restore the Array 1100 constructive-algorithms, greedy 4m 56s ✗
D Umka and a Long Flight 1600 constructive-algorithms, implementation, math 1m 38s ✗
E Living Sequence 1500 binary-search, dp, math 1m 16s ✓
F Is It Flower? 2100 dfs-and-similar, graphs, implementation 1m 46s ✓
G1 Vlad and the Nice Paths (easy version) 2100 combinatorics, dp, math 1m 48s ✗
G2 Vlad and the Nice Paths (hard version) 2200 binary-search, combinatorics, data-structures 1m 26s ✗
Practice › Codeforces Solutions › Codeforces Round 863 (Div. 3) ›

CF 1811G2 - Vlad and the Nice Paths (hard version)

We have a row of tiles, each painted with a color. Vlad wants to create paths along this row such that the path can be divided into consecutive blocks of length k, and each block consists of identical colors. We are asked to find all "nice paths" of maximum possible length.
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CF 1811G1 - Vlad and the Nice Paths (easy version)

We are given a row of tiles, each with a color, and an integer $k$. A path is formed by jumping to tiles to the right, and a path is called "nice" if its length is divisible by $k$ and the colors are constant in contiguous blocks of size $k$.
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CF 1811C - Restore the Array

We are given a derived array $b$, and we are told it comes from some hidden array $a$. Each value $bi$ is the maximum of two adjacent values in $a$, specifically $ai$ and $a{i+1}$.
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CF 1811F - Is It Flower?

We are asked to detect a specific type of graph called a $k$-flower. Conceptually, a $k$-flower is made of a central cycle of length $k$, and at each vertex of that cycle there is another disjoint cycle of length $k$ attached.
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CF 1811D - Umka and a Long Flight

We are given a rectangle whose dimensions are tied to Fibonacci numbers. Its height is $Fn$ and its width is $F{n+1}$, where the Fibonacci sequence starts with $F0 = F1 = 1$. Inside this grid, one specific cell is marked.
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CF 1811E - Living Sequence

We are asked to generate the k-th number in a sequence of natural numbers that do not contain the digit 4. The sequence starts as [1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, ...].
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CF 1811B - Conveyor Belts

We are given an $n times n$ matrix, where $n$ is always even. The matrix is built as concentric layers, each layer forming a cycle that moves clockwise. You start at a given cell $(x1, y1)$ and want to reach another cell $(x2, y2)$.
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CF 1811A - Insert Digit

We are given a decimal number written as a string and a single extra digit. We are allowed to insert this digit at any position in the number, including before the first digit or after the last digit.
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