Codeforces Round 841 (Div. 2) and Divide by Zero 2022

6 problems from Codeforces Round 841 (Div. 2) and Divide by Zero 2022 (contest 1731), difficulty 800-2500. 5/6 solutions verified against sample I/O.

6 items

Codeforces Round 841 (Div. 2) and Divide by Zero 2022

Div. 2 | 6 problems | 5/6 verified | Difficulty 800-2500 | 26m 51s

# Problem Rating Tags Accepted Time ✓
A Joey Takes Money 800 greedy, math 23,667 1m 54s ✓
B Kill Demodogs 1100 greedy, math 26,784 8m 50s
C Even Subarrays 1700 bitmasks, brute-force, hashing 12,125 3m 54s ✓
D Valiant's New Map 1700 binary-search, brute-force, data-structures 8,494 5m 57s ✓
E Graph Cost 2000 dp, greedy, math 3,484 3m 57s ✓
F Function Sum 2500 brute-force, combinatorics, dp 853 2m 19s ✓
Practice › Codeforces Solutions › Codeforces Round 841 (Div. 2) and Divide by Zero 2022 ›

CF 1731B - Kill Demodogs

We are working on an $n times n$ grid where each cell $(i, j)$ contains a value equal to the product $i cdot j$. A character starts at the top-left corner $(1, 1)$ and must reach the bottom-right corner $(n, n)$, moving only right or down at each step.
codeforces competitive-programming greedy math Jun 15, 2026
Practice › Codeforces Solutions › Codeforces Round 841 (Div. 2) and Divide by Zero 2022 ›

CF 1731E - Graph Cost

We start with a graph of $n$ labeled vertices and no edges. The goal is to end with exactly $m$ undirected edges. Each edge between vertices $u$ and $v$ is not freely chosen: its weight is fixed and equals $gcd(u, v)$.
codeforces competitive-programming dp greedy math number-theory Jun 15, 2026
Practice › Codeforces Solutions › Codeforces Round 841 (Div. 2) and Divide by Zero 2022 ›

CF 1731D - Valiant's New Map

We are given several independent grids, each grid representing a city map where every cell contains a building height. From each grid, we must choose a square subgrid of size $l times l$ such that every cell inside that square has height at least $l$.
codeforces competitive-programming binary-search brute-force data-structures dp two-pointers Jun 15, 2026
Practice › Codeforces Solutions › Codeforces Round 841 (Div. 2) and Divide by Zero 2022 ›

CF 1731C - Even Subarrays

We are given an array of integers, and we look at every contiguous segment of it. For each segment we compute the bitwise XOR of its elements, producing a single number.
codeforces competitive-programming bitmasks brute-force hashing math number-theory Jun 15, 2026
Practice › Codeforces Solutions › Codeforces Round 841 (Div. 2) and Divide by Zero 2022 ›

CF 1731F - Function Sum

We are asked to work with arrays of integers of size n, where each element is between 1 and k. For each position in the array, we define two quantities.
codeforces competitive-programming brute-force combinatorics dp fft math Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 841 (Div. 2) and Divide by Zero 2022 ›

CF 1731A - Joey Takes Money

We are given an array of positive integers representing amounts of money Joey can "manipulate" through a sequence of operations.
codeforces competitive-programming greedy math Jun 9, 2026