Codeforces Round 891 (Div. 3)

Solutions for Codeforces Round 891 (Div. 3) (contest 1857). 1/7 problems verified against sample I/O. Difficulty range: 800-2000.

7 items

Codeforces Round 891 (Div. 3)

Type: Div. 3 | Problems: 7 | Verified: 1/7 | Rating range: 800-2000 | Time: 12m 41s

Problem Name Rating Tags Solve Time Verified
A Array Coloring 800 greedy, math 1m 18s ✓
B Maximum Rounding 1100 greedy, implementation, math 1m 38s ✗
C Assembly via Minimums 1200 greedy, sortings 2m 11s ✗
D Strong Vertices 1300 math, sortings, trees 1m 46s ✗
E Power of Points 1500 math, sortings 1m 44s ✗
F Sum and Product 1600 binary-search, data-structures, math 2m 9s ✗
G Counting Graphs 2000 combinatorics, divide-and-conquer, dsu 1m 55s ✗
Practice › Codeforces Solutions › Codeforces Round 891 (Div. 3) ›

CF 1857G - Counting Graphs

We are given a tree on $n$ vertices, where each edge has an integer weight. The task is to count the number of weighted simple graphs such that the given tree is the unique minimum spanning tree (MST), and all edge weights in the graph are integers not exceeding $S$.
codeforces competitive-programming combinatorics divide-and-conquer dsu graphs greedy sortings trees Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 891 (Div. 3) ›

CF 1857F - Sum and Product

The traceback already tells us that the current program is not failing because of the algorithm itself. It is failing because the code is reading the input incorrectly and then indexing past the end of the array.
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Practice › Codeforces Solutions › Codeforces Round 891 (Div. 3) ›

CF 1857E - Power of Points

We are given several test cases. In each test case, we start with a list of points placed on a number line. For every point we choose one special position s, and we connect s to every point xi by a segment on the integer line.
codeforces competitive-programming math sortings Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 891 (Div. 3) ›

CF 1857D - Strong Vertices

We are given two arrays, a and b, both of length n. From these arrays, we are asked to construct a directed graph with n vertices. There is an edge from vertex u to vertex v (for u != v) if the difference a[u] - a[v] is greater than or equal to b[u] - b[v].
codeforces competitive-programming math sortings trees Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 891 (Div. 3) ›

CF 1857C - Assembly via Minimums

The traceback already tells us that the current program is not failing because of the algorithm itself. It is failing because the code is reading the input incorrectly and then indexing past the end of the array.
codeforces competitive-programming greedy sortings Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 891 (Div. 3) ›

CF 1857B - Maximum Rounding

We are given a number written as a string of digits, and we are allowed to repeatedly apply a specific rounding operation that changes digits at a chosen position and propagates carry to higher positions in a non-standard way.
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Practice › Codeforces Solutions › Codeforces Round 891 (Div. 3) ›

CF 1857A - Array Coloring

We are given an array of integers and need to decide whether it can be partitioned into two non-empty groups such that the sums of each group have the same parity-both even or both odd. Each group must contain at least one element.
codeforces competitive-programming greedy math Jun 9, 2026