Codeforces Round 104 (Div. 2)

Solutions for Codeforces Round 104 (Div. 2) (contest 146). 2/2 problems verified against sample I/O. Difficulty range: 800-1300.

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Codeforces Round 104 (Div. 2)

Type: Div. 2 | Problems: 2 | Verified: 2/2 | Rating range: 800-1300 | Time: 2m 40s

Problem Name Rating Tags Solve Time Verified
A Lucky Ticket 800 implementation 1m 10s ✓
B Lucky Mask 1300 brute-force, implementation 1m 30s ✓
Practice › Codeforces Solutions › Codeforces Round 104 (Div. 2) ›

CF 146A - Lucky Ticket

We are asked to determine whether a ticket number is lucky. A lucky ticket number satisfies two conditions simultaneously. First, every digit of the number must be either 4 or 7.
codeforces competitive-programming implementation May 29, 2026
Practice › Codeforces Solutions › Codeforces Round 104 (Div. 2) ›

CF 146B - Lucky Mask

We are given two integers. The first number, a, is arbitrary. The second number, b, is guaranteed to be lucky, meaning every digit of b is either 4 or 7. For any positive integer, its "mask" is formed by taking only the digits 4 and 7 from left to right and concatenating them.
codeforces competitive-programming brute-force implementation May 29, 2026