Codeforces Beta Round 17

Solutions for Codeforces Beta Round 17 (contest 17). 4/5 problems verified against sample I/O. Difficulty range: 1000-2900.

5 items

Codeforces Beta Round 17

Type: Beta | Problems: 5 | Verified: 4/5 | Rating range: 1000-2900 | Time: 16m 51s

Problem Name Rating Tags Solve Time Verified
A Noldbach problem 1000 brute-force, math, number-theory 1m 46s ✓
B Hierarchy 1500 dfs-and-similar, dsu, greedy 1m 34s ✓
C Balance 2500 dp 6m 37s ✗
D Notepad 2400 number-theory 3m 4s ✓
E Palisection 2900 strings 3m 50s ✓
Practice › Codeforces Solutions › Codeforces Beta Round 17 ›

CF 17A - Noldbach problem

We are given two integers, n and k. We look at all prime numbers from 2 up to n. Among those primes, we want to count how many can be written in the form:
codeforces competitive-programming brute-force math number-theory May 28, 2026
Practice › Codeforces Solutions › Codeforces Beta Round 17 ›

CF 17B - Hierarchy

We have employees and directed supervisor offers between them. An offer (a, b, c) means employee a is willing to supervise employee b for cost c. Qualifications are strictly decreasing along every offer, so q[a] > q[b].
codeforces competitive-programming dfs-and-similar dsu greedy shortest-paths May 28, 2026
Practice › Codeforces Solutions › Codeforces Beta Round 17 ›

CF 17C - Balance

We are given a string consisting of characters a, b, and c, and we are allowed to repeatedly perform two types of operations: copy the left character of any adjacent pair onto the right, or copy the right character onto the left.
codeforces competitive-programming dp May 28, 2026
Practice › Codeforces Solutions › Codeforces Beta Round 17 ›

CF 17D - Notepad

Nick wants to list all numbers of a given length n in base b, where digits range from 0 to b-1, but numbers cannot start with 0. Each page in his notepad holds exactly c numbers. We are asked to compute how many numbers appear on the last page he fills.
codeforces competitive-programming number-theory May 28, 2026
Practice › Codeforces Solutions › Codeforces Beta Round 17 ›

CF 17E - Palisection

We are given a string and we consider every palindromic substring inside it. Each occurrence matters separately, even if two substrings have the same text. For example, in "aaa" there are three different occurrences of "a".
codeforces competitive-programming strings May 28, 2026