Educational Codeforces Round 178 (Rated for Div. 2)

7 problems from Educational Codeforces Round 178 (Rated for Div. 2) (contest 2104), difficulty 800-2700. 3/7 solutions verified against sample I/O.

7 items

Educational Codeforces Round 178 (Rated for Div. 2)

Div. 2 | 7 problems | 3/7 verified | Difficulty 800-2700 | 11m 3s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Three Decks	800	math	26,298	1m 41s	✓
B	Move to the End	1000	brute-force, data-structures, dp	20,750	1m 37s
C	Card Game	1100	brute-force, constructive-algorithms, games	17,377	1m 19s	✓
D	Array and GCD	1400	binary-search, greedy, math	13,226	1m 39s	✓
E	Unpleasant Strings	1700	binary-search, dp, greedy	8,085	1m 35s
F	Numbers and Strings	2600	binary-search, brute-force, dfs-and-similar	725	1m 45s
G	Modulo 3	2700	data-structures, divide-and-conquer, dsu	534	1m 27s

Practice › Codeforces Solutions › Educational Codeforces Round 178 (Rated for Div. 2) ›

CF 2104G - Modulo 3

We are given a functional graph, meaning each vertex has exactly one outgoing edge. This forms a combination of cycles and trees pointing into those cycles.

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CF 2104F - Numbers and Strings

We are asked to count the number of distinct strings generated by a simple, but slightly tricky rule. For each integer $x$ from 1 up to $n$, we form a string by concatenating $x$ and $x+1$, then sorting the digits of this concatenation.

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CF 2104E - Unpleasant Strings

We are given a fixed reference string s, and we are allowed to use only the first k lowercase letters. From this string s, we consider any string t to be “valid” if it can be formed by deleting characters from s without changing order, meaning t is a subsequence of s.

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CF 2104D - Array and GCD

We are given an array of integers and we are allowed to modify it using a very specific resource system. Each increment of any element costs one coin, and each decrement of any element gives one coin.

Practice › Codeforces Solutions › Educational Codeforces Round 178 (Rated for Div. 2) ›

CF 2104A - Three Decks

We are given three stacks of cards arranged in a row, with the first stack containing a cards, the second b cards, and the third c cards. The numbers satisfy a < b < c.

Practice › Codeforces Solutions › Educational Codeforces Round 178 (Rated for Div. 2) ›

CF 2104B - Move to the End

We are given an array of integers, and for every possible length $k$ from 1 to $n$, we want to maximize the sum of the last $k$ elements after moving one element of our choice to the end of the array. After we choose and move that element, we restore the array for the next query.

Practice › Codeforces Solutions › Educational Codeforces Round 178 (Rated for Div. 2) ›

CF 2104C - Card Game

We are given a small card game where each card is uniquely labeled from 1 to n, and each card initially belongs to either Alice or Bob. The ownership is fixed at the start, but during the game cards can move between players depending on outcomes.