Educational Codeforces Round 81 (Rated for Div. 2)

5 problems from Educational Codeforces Round 81 (Rated for Div. 2) (contest 1295), difficulty 1600-2700. 3/5 solutions verified against sample I/O.

5 items

Educational Codeforces Round 81 (Rated for Div. 2)

Div. 2 | 5 problems | 3/5 verified | Difficulty 1600-2700 | 13m 45s

#	Problem	Rating	Tags	Accepted	Time	✓
B	Infinite Prefixes	1700	math, strings	9,870	3m 1s
C	Obtain The String	1600	dp, greedy, strings	13,840	1m 42s	✓
D	Same GCDs	1800	math, number-theory	10,209	3m 37s	✓
E	Permutation Separation	2200	data-structures, divide-and-conquer	2,771	3m 40s
F	Good Contest	2700	combinatorics, dp, probabilities	1,507	1m 45s	✓

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CF 1295E - Permutation Separation

We are given a permutation where every value from 1 to n appears exactly once, but the order is arbitrary. Each position also has a cost associated with its element, and that cost is what we pay whenever we move that element between two groups.

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CF 1295D - Same GCDs

We are working with a fixed number $a$ and a modulus-like bound $m$. For every integer shift $x$ in the range $[0, m-1]$, we look at the number $a + x$ and compare its greatest common divisor with $m$ against the original value $gcd(a, m)$.

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CF 1295F - Good Contest

We are given a contest with n problems, where each problem i has a range [li, ri] representing the possible number of accepted solutions. Each integer in this range is equally likely, and selections for different problems are independent.

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CF 1295B - Infinite Prefixes

There is not enough information to diagnose the bug or provide a corrected solution. The sample with expected output appears to belong to a string construction problem, but you have not provided: - the problem statement, - the original Python solution, - or even the name of…

Practice › Codeforces Solutions › Educational Codeforces Round 81 (Rated for Div. 2) ›

CF 1295C - Obtain The String

We are given two strings, s and t. Initially, we have an empty string z, and we want to transform z into t. The allowed operation is to append any subsequence of s to z. A subsequence is formed by selecting characters from s without changing their relative order.