Educational Codeforces Round 72 (Rated for Div. 2)

6 problems from Educational Codeforces Round 72 (Rated for Div. 2) (contest 1217), difficulty 1300-2600. 5/6 solutions verified against sample I/O.

6 items

Educational Codeforces Round 72 (Rated for Div. 2)

Div. 2 | 6 problems | 5/6 verified | Difficulty 1300-2600 | 25m 8s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Creating a Character	1300	binary-search, math	15,823	5m 30s	✓
B	Zmei Gorynich	1600	greedy, math	11,856	5m 17s	✓
C	The Number Of Good Substrings	1700	binary-search, bitmasks, brute-force	7,856	1m 48s	✓
D	Coloring Edges	2100	constructive-algorithms, dfs-and-similar, graphs	5,941	2m 41s	✓
E	Sum Queries?	2300	data-structures, greedy, implementation	2,062	4m 41s	✓
F	Forced Online Queries Problem	2600	data-structures, divide-and-conquer, dsu	722	5m 11s

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CF 1217F - Forced Online Queries Problem

The graph starts empty, but it is continuously modified by two types of operations. The first operation toggles an edge between two vertices, and the second operation asks whether two vertices are connected in the current graph.

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CF 1217A - Creating a Character

We are given a character with two base attributes: strength and intelligence. We are also given a pool of extra experience points that must all be distributed. Each point can increase either strength or intelligence by exactly one unit.

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CF 1217E - Sum Queries?

We are given an array of integers that changes over time, and we are repeatedly asked to inspect a chosen segment of this array.

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CF 1217D - Coloring Edges

We are given a directed graph where each edge is fixed in advance, and we must assign a color (an integer label) to every edge. The constraint is not about vertices but about directed cycles: if you look at all edges of a single color, they must not contain any directed cycle.

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CF 1217B - Zmei Gorynich

We are given a creature with an initial number of heads, and a collection of attack types. Each attack type behaves in a very specific way: when used, it removes some number of heads, but after the strike, if the creature is still alive, it immediately regrows a fixed number…

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CF 1217C - The Number Of Good Substrings

We are given a binary string and asked to count its "good" substrings. A substring is good if its length equals the decimal value of its binary representation, allowing leading zeros.