Educational Codeforces Round 65 (Rated for Div. 2)

6 problems from Educational Codeforces Round 65 (Rated for Div. 2) (contest 1167), difficulty 800-3100. 3/6 solutions verified against sample I/O.

6 items

Educational Codeforces Round 65 (Rated for Div. 2)

Div. 2 | 6 problems | 3/6 verified | Difficulty 800-3100 | 22m 34s

# Problem Rating Tags Accepted Time ✓
A Telephone Number 800 brute-force, greedy, strings 20,276 2m 3s ✓
B Lost Numbers 1400 brute-force, divide-and-conquer, interactive 16,459 3m 4s
C News Distribution 1400 dfs-and-similar, dsu, graphs 25,981 3m 18s ✓
D Bicolored RBS 1500 constructive-algorithms, greedy 7,369 2m 39s ✓
F Scalar Queries 2300 combinatorics, data-structures, math 1,890 5m 46s
G Low Budget Inception 3100 brute-force, geometry 166 5m 44s
Practice › Codeforces Solutions › Educational Codeforces Round 65 (Rated for Div. 2) ›

CF 1167F - Scalar Queries

We are given an array of distinct numbers, and we look at every possible contiguous subarray. For each subarray, we do not use its original order directly.
codeforces competitive-programming combinatorics data-structures math sortings Jun 15, 2026
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CF 1167B - Lost Numbers

We are given a hidden permutation of six fixed numbers: 4, 8, 15, 16, 23, and 42. Each number appears exactly once, but their order is unknown. Our task is to reconstruct this ordering. We do not see the array directly.
codeforces competitive-programming brute-force divide-and-conquer interactive math Jun 15, 2026
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CF 1167G - Low Budget Inception

We are given a set of unit squares placed along the x-axis. Each building occupies a segment from $ai$ to $ai+1$ at height $0$ to $1$. The buildings are ordered left to right and do not overlap, but gaps between consecutive buildings are bounded by a given value.
codeforces competitive-programming brute-force geometry Jun 13, 2026
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CF 1167D - Bicolored RBS

We are given a valid parentheses string. Think of it as a walk that starts at height 0, where every opening bracket increases the height by 1 and every closing bracket decreases it by 1, and the walk never goes negative and ends at 0.
codeforces competitive-programming constructive-algorithms greedy Jun 13, 2026
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CF 1167A - Telephone Number

We are given a string of digits and we are allowed to delete characters freely, without changing the relative order of the remaining digits. The task is to decide whether we can extract a subsequence of length exactly 11 that forms a valid telephone number.
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CF 1167C - News Distribution

We are given a social network with n users and m groups of friends. Each group contains a list of users who are mutually friends with each other.
codeforces competitive-programming dfs-and-similar dsu graphs Jun 12, 2026