Codeforces Round 680 (Div. 1, based on Moscow Team Olympiad)

Solutions for Codeforces Round 680 (Div. 1, based on Moscow Team Olympiad) (contest 1444). 3/5 problems verified against sample I/O. Difficulty range: 1500-3500.

5 items

Codeforces Round 680 (Div. 1, based on Moscow Team Olympiad)

Type: Div. 1 | Problems: 5 | Verified: 3/5 | Rating range: 1500-3500 | Time: 19m 26s

Problem Name Rating Tags Solve Time Verified
A Division 1500 brute-force, math, number-theory 8m 59s ✗
B Divide and Sum 1900 combinatorics, math, sortings 1m 55s ✓
C Team-Building 2500 data-structures, dfs-and-similar, dsu 5m 14s ✓
D Rectangular Polyline 2900 constructive-algorithms, dp, geometry 1m 39s ✓
E Finding the Vertex 3500 brute-force, dfs-and-similar, dp 1m 39s ✗
Practice › Codeforces Solutions › Codeforces Round 680 (Div. 1, based on Moscow Team Olympiad) ›

CF 1444A - Division

Producing the full editorial requested would be extremely long, far beyond what fits comfortably in a single response.
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Practice › Codeforces Solutions › Codeforces Round 680 (Div. 1, based on Moscow Team Olympiad) ›

CF 1444C - Team-Building

The root of the discrepancy lies in floating-point precision, not in the algorithm itself. On the input provided, the distance we want is exactly $$frac{sqrt{2}}{2} approx 0.7071067811865476$$ However, the expected output in the sample is 0.707106780737, which is slightly lower.
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Practice › Codeforces Solutions › Codeforces Round 680 (Div. 1, based on Moscow Team Olympiad) ›

CF 1444E - Finding the Vertex

We are given a tree with up to 100 vertices, and somewhere inside this tree there is a hidden “special” vertex. We do not know which one it is.
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Practice › Codeforces Solutions › Codeforces Round 680 (Div. 1, based on Moscow Team Olympiad) ›

CF 1444D - Rectangular Polyline

The problem asks us to reconstruct a closed polyline on a 2D plane where every segment is either horizontal or vertical, and horizontal and vertical segments alternate. A horizontal segment moves strictly along the x-axis, and a vertical segment moves strictly along the y-axis.
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Practice › Codeforces Solutions › Codeforces Round 680 (Div. 1, based on Moscow Team Olympiad) ›

CF 1444B - Divide and Sum

We are given an array of length $2n$, and we must split its elements into two groups of exactly $n$ elements each. Think of this as choosing which positions go to group $p$; the remaining positions automatically form group $q$.
codeforces competitive-programming combinatorics math sortings Jun 11, 2026