Codeforces Round 796 (Div. 1)

Solutions for Codeforces Round 796 (Div. 1) (contest 1687). 2/6 problems verified against sample I/O. Difficulty range: 1600-3500.

6 items

Codeforces Round 796 (Div. 1)

Type: Div. 1 | Problems: 6 | Verified: 2/6 | Rating range: 1600-3500 | Time: 12m 43s

Problem Name Rating Tags Solve Time Verified
A The Enchanted Forest 1600 brute-force, greedy 2m 3s ✗
B Railway System 1700 constructive-algorithms, graphs, greedy 1m 50s ✗
C Sanae and Giant Robot 2500 binary-search, brute-force, data-structures 2m 31s ✗
D Cute number 2900 binary-search, brute-force, data-structures 2m 34s ✓
E Become Big For Me 3500 combinatorics, constructive-algorithms, greedy 1m 26s ✓
F Koishi's Unconscious Permutation 3500 fft, math 2m 19s ✗
Practice › Codeforces Solutions › Codeforces Round 796 (Div. 1) ›

CF 1687F - Koishi's Unconscious Permutation

The solution addresses the exercise directly. It identifies the event $f(n)-f(n-1) = k$ as the occurrence of exactly $k-1$ consecutive terms outside the interval $[alpha,beta)$ followed by one term inside, which correctly models the "gap" between hits in the interval.
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Practice › Codeforces Solutions › Codeforces Round 796 (Div. 1) ›

CF 1687D - Cute number

For every integer, look at the two consecutive perfect squares surrounding it. If $$m^2 le x < (m+1)^2,$$ then $g(x)=m^2$ and $f(x)=(m+1)^2$. The number is called cute when it is strictly closer to the lower square than to the upper square.
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Practice › Codeforces Solutions › Codeforces Round 796 (Div. 1) ›

CF 1687E - Become Big For Me

We are given a sequence of integers a and a number v initialized to 1. The task is to perform a series of operations on v so that it becomes the greatest common divisor of all pairwise products of elements from a.
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Practice › Codeforces Solutions › Codeforces Round 796 (Div. 1) ›

CF 1687C - Sanae and Giant Robot

The solution addresses the exercise directly. It identifies the event $f(n)-f(n-1) = k$ as the occurrence of exactly $k-1$ consecutive terms outside the interval $[alpha,beta)$ followed by one term inside, which correctly models the "gap" between hits in the interval.
codeforces competitive-programming binary-search brute-force data-structures dsu greedy sortings Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 796 (Div. 1) ›

CF 1687A - The Enchanted Forest

We are asked to compute the maximum number of mushrooms Marisa can collect in a one-dimensional forest over a limited number of minutes.
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Practice › Codeforces Solutions › Codeforces Round 796 (Div. 1) ›

CF 1687B - Railway System

We are given a railway network consisting of n stations and m bidirectional tracks, each with a positive length. The network may not be fully connected and can have multiple tracks between the same pair of stations.
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