Yandex.Algorithm 2011: Round 1

Solutions for Yandex.Algorithm 2011: Round 1 (contest 85). 5/5 problems verified against sample I/O. Difficulty range: 1300-2600.

5 items

Yandex.Algorithm 2011: Round 1

Type: Special | Problems: 5 | Verified: 5/5 | Rating range: 1300-2600 | Time: 11m 13s

Problem Name Rating Tags Solve Time Verified
A Domino 1300 constructive-algorithms, implementation 2m 9s ✓
B Embassy Queue 1800 data-structures, greedy 2m 1s ✓
C Petya and Tree 2200 binary-search, dfs-and-similar, probabilities 2m 4s ✓
D Sum of Medians 2300 binary-search, brute-force, data-structures 1m 18s ✓
E Guard Towers 2600 binary-search, dsu, geometry 3m 41s ✓
Practice › Codeforces Solutions › Yandex.Algorithm 2011: Round 1 ›

CF 85A - Domino

We need to tile a 4 × n board using ordinary dominoes. Each domino covers exactly two neighboring cells, either horizontally or vertically. The tiling must satisfy an extra condition.
codeforces competitive-programming constructive-algorithms implementation May 28, 2026
Practice › Codeforces Solutions › Yandex.Algorithm 2011: Round 1 ›

CF 85B - Embassy Queue

Each person visiting the embassy must pass through three consecutive stages. The first stage has k1 identical windows, each service taking t1 time. The second stage has k2 windows with service time t2, and the third stage has k3 windows with service time t3.
codeforces competitive-programming data-structures greedy May 28, 2026
Practice › Codeforces Solutions › Yandex.Algorithm 2011: Round 1 ›

CF 85C - Petya and Tree

We are given a valid binary search tree where every internal node has exactly two children. Each node stores a unique key. We are also given several query keys that are guaranteed not to appear in the tree. A normal BST search starts at the root.
codeforces competitive-programming binary-search dfs-and-similar probabilities sortings trees May 28, 2026
Practice › Codeforces Solutions › Yandex.Algorithm 2011: Round 1 ›

CF 85D - Sum of Medians

We are asked to maintain a dynamic set of positive integers under three operations: adding a number, deleting a number, and computing the sum of medians of every consecutive group of five elements after sorting the set.
codeforces competitive-programming binary-search brute-force data-structures implementation May 28, 2026
Practice › Codeforces Solutions › Yandex.Algorithm 2011: Round 1 ›

CF 85E - Guard Towers

We have n towers on a 2D plane. Every tower must belong to exactly one of two generals. For each general, the cost he demands is the maximum Manhattan distance between any two towers assigned to him. The king only pays the larger of the two costs.
codeforces competitive-programming binary-search dsu geometry graphs sortings May 28, 2026