Codeforces Round 641 (Div. 2)

2 problems from Codeforces Round 641 (Div. 2) (contest 1350), difficulty 900-1400. 2/2 solutions verified against sample I/O.

2 items

Codeforces Round 641 (Div. 2)

Div. 2 | 2 problems | 2/2 verified | Difficulty 900-1400 | 7m 24s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Orac and Factors	900	math	27,374	5m 48s	✓
B	Orac and Models	1400	dp, math, number-theory	29,431	1m 36s	✓

Practice › Codeforces Solutions › Codeforces Round 641 (Div. 2) ›

CF 1350A - Orac and Factors

We start with a number and repeatedly apply a very specific transformation: find its smallest divisor greater than 1, and add that value to the number. This operation changes the number itself, so the divisor we use may change at every step.

Practice › Codeforces Solutions › Codeforces Round 641 (Div. 2) ›

CF 1350B - Orac and Models

We are given several independent test cases. In each one, we have a sequence of model sizes indexed from 1 to n. We are allowed to pick a subset of indices, but the chosen indices must be kept in increasing order, which is equivalent to choosing a subsequence of indices.