Codeforces Round 168 (Div. 1)

5 problems from Codeforces Round 168 (Div. 1) (contest 274), difficulty 1500-3000. 4/5 solutions verified against sample I/O.

5 items

Codeforces Round 168 (Div. 1)

Div. 1 | 5 problems | 4/5 verified | Difficulty 1500-3000 | 6m 59s

#	Problem	Rating	Tags	Accepted	Time	✓
A	k-Multiple Free Set	1500	binary-search, greedy, sortings	10,812	1m 6s	✓
B	Zero Tree	1800	dfs-and-similar, dp, greedy	5,570	1m 11s	✓
C	The Last Hole!	2600	brute-force, geometry	376	1m 12s	✓
D	Lovely Matrix	2200	dfs-and-similar, graphs, greedy	1,155	1m 34s	✓
E	Mirror Room	3000	data-structures, implementation	341	1m 56s

Practice › Codeforces Solutions › Codeforces Round 168 (Div. 1) ›

CF 274B - Zero Tree

The input describes a tree where every vertex holds an integer value. The only allowed operation is global but structurally restricted: you pick a connected region that must contain vertex 1, and then you add either +1 or -1 to every value in that region.

Practice › Codeforces Solutions › Codeforces Round 168 (Div. 1) ›

CF 274A - k-Multiple Free Set

We are given a collection of distinct positive integers, and we want to select as many of them as possible while avoiding a specific type of forbidden relationship.

Practice › Codeforces Solutions › Codeforces Round 168 (Div. 1) ›

CF 274E - Mirror Room

We are asked to simulate a laser beam moving through a two-dimensional grid. Each cell in the grid is either empty or blocked. The beam starts from a specific empty cell and moves diagonally in one of four directions: north-east, north-west, south-east, or south-west.

Practice › Codeforces Solutions › Codeforces Round 168 (Div. 1) ›

CF 274D - Lovely Matrix

We are given a matrix with n rows and m columns. Each row originally was sorted in non-decreasing order, but now some entries have been erased (marked -1) and the columns may have been shuffled.

Practice › Codeforces Solutions › Codeforces Round 168 (Div. 1) ›

CF 274C - The Last Hole!

We are given several points on a plane, each representing the center of a circle. These circles begin to grow at the same time, with their radius increasing linearly over time. A hole is any connected white region that is completely enclosed by black circles.