Codeforces Round 851 (Div. 2)

Solutions for Codeforces Round 851 (Div. 2) (contest 1788). 4/6 problems verified against sample I/O. Difficulty range: 800-2500.

6 items

Codeforces Round 851 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 4/6 | Rating range: 800-2500 | Time: 10m 18s

Problem Name Rating Tags Solve Time Verified
A One and Two 800 brute-force, implementation, math 1m 51s ✓
B Sum of Two Numbers 1100 constructive-algorithms, greedy, implementation 2m 1s ✗
C Matching Numbers 1300 constructive-algorithms, greedy, math 1m 51s ✗
D Moving Dots 2000 binary-search, brute-force, combinatorics 1m 31s ✓
E Sum Over Zero 2200 data-structures, dfs-and-similar, dp 1m 31s ✓
F XOR, Tree, and Queries 2500 bitmasks, constructive-algorithms, dfs-and-similar 1m 33s ✓
Practice › Codeforces Solutions › Codeforces Round 851 (Div. 2) ›

Practice › Codeforces Solutions › Codeforces Round 851 (Div. 2) ›

CF 1788F - XOR, Tree, and Queries

We have a tree with $n$ vertices and $n-1$ edges. We must assign a non-negative integer weight to every edge. Some constraints are given in the form $(u,v,x)$, meaning that the XOR of all edge weights along the unique path between $u$ and $v$ must equal $x$.
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CF 1788E - Sum Over Zero

We are given an array of integers and want to choose several segments on it. Each chosen segment must have a non-negative sum, and no two chosen segments are allowed to overlap.
codeforces competitive-programming data-structures dfs-and-similar dp Jun 9, 2026
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CF 1788D - Moving Dots

We are given a set of $n$ distinct dots positioned on a number line. Each dot moves toward the nearest other dot, stopping when it meets another dot. If a dot has two equally close neighbors, it moves left. Once dots meet, they merge into a single stationary point.
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CF 1788A - One and Two

We are given a sequence of numbers where each element is either 1 or 2. Our goal is to split the sequence into two contiguous parts such that the product of numbers in the first part equals the product of numbers in the second part.
codeforces competitive-programming brute-force implementation math Jun 9, 2026
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CF 1788C - Matching Numbers

The task asks us to pair up all integers from 1 to 2n into exactly n pairs, such that the sums of the pairs form a sequence of consecutive integers.
codeforces competitive-programming constructive-algorithms greedy math Jun 9, 2026