Codeforces Round 643 (Div. 2)

4 problems from Codeforces Round 643 (Div. 2) (contest 1355), difficulty 1200-2600. 3/4 solutions verified against sample I/O.

4 items

Codeforces Round 643 (Div. 2)

Div. 2 | 4 problems | 3/4 verified | Difficulty 1200-2600 | 18m 43s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Sequence with Digits	1200	brute-force, implementation, math	28,801	3m 58s	✓
B	Young Explorers	1200	dp, greedy, sortings	27,370	7m 34s	✓
D	Game With Array	1400	constructive-algorithms, math	19,055	2m 50s	✓
F	Guess Divisors Count	2600	constructive-algorithms, interactive, number-theory	964	4m 21s

Practice › Codeforces Solutions › Codeforces Round 643 (Div. 2) ›

CF 1355F - Guess Divisors Count

We are given a hidden integer $X$ in each game, but we are never allowed to see it directly. Instead, we can query any integer $Q$, and the judge returns $gcd(X, Q)$.

Practice › Codeforces Solutions › Codeforces Round 643 (Div. 2) ›

CF 1355D - Game With Array

We are asked to construct a positive integer array of length $N$ whose total sum is exactly $S$. After building this array, we also choose an integer $K$ between $0$ and $S$.

Practice › Codeforces Solutions › Codeforces Round 643 (Div. 2) ›

We are given a list of explorers, each associated with a number $ei$ that represents how many people must be in any group they join. If an explorer has value $e$, then they are only willing to participate in a group whose size is at least $e$.

Practice › Codeforces Solutions › Codeforces Round 643 (Div. 2) ›

CF 1355A - Sequence with Digits

We are asked to generate a sequence of numbers defined recursively. The sequence starts with a given number $a1$, and each subsequent number is obtained by adding the product of the minimum and maximum digits of the previous number.

Codeforces Round 643 (Div. 2)

Codeforces Round 643 (Div. 2)

CF 1355F - Guess Divisors Count

CF 1355D - Game With Array

CF 1355B - Young Explorers

CF 1355A - Sequence with Digits