Codeforces Beta Round 91 (Div. 2 Only)

2 problems from Codeforces Beta Round 91 (Div. 2 Only) (contest 122), difficulty 1000-1000. 2/2 solutions verified against sample I/O.

2 items

Codeforces Beta Round 91 (Div. 2 Only)

Div. 2 | 2 problems | 2/2 verified | Difficulty 1000-1000 | 2m 30s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Lucky Division	1000	brute-force, number-theory	149,745	1m 12s	✓
B	Lucky Substring	1000	brute-force, implementation	13,264	1m 18s	✓

Practice › Codeforces Solutions › Codeforces Beta Round 91 (Div. 2 Only) ›

CF 122A - Lucky Division

We are asked to determine whether a given number is almost lucky. A number is almost lucky if it is divisible by at least one lucky number. Lucky numbers are positive integers composed entirely of the digits 4 and 7, like 4, 7, 44, 47, 74, and so on.

Practice › Codeforces Solutions › Codeforces Beta Round 91 (Div. 2 Only) ›

CF 122B - Lucky Substring

The problem asks us to find the "luckiest" substring of a given string of digits. By luckiest, we mean a substring that consists only of the digits 4 and 7, occurs in the string as many times as possible, and is the lexicographically smallest if there are ties.