Codeforces Beta Round 30 (Codeforces format)

Solutions for Codeforces Beta Round 30 (Codeforces format) (contest 30). 4/5 problems verified against sample I/O. Difficulty range: 1400-2800.

5 items

Codeforces Beta Round 30 (Codeforces format)

Type: Beta | Problems: 5 | Verified: 4/5 | Rating range: 1400-2800 | Time: 7m 26s

Problem Name Rating Tags Solve Time Verified
A Accounting 1400 brute-force, math 1m 23s ✓
B Codeforces World Finals 1700 implementation 1m 1s ✓
C Shooting Gallery 1800 dp, probabilities 1m ✓
D King's Problem? 2600 geometry, greedy 2m 12s ✗
E Tricky and Clever Password 2800 binary-search, constructive-algorithms, data-structures 1m 50s ✓
Practice › Codeforces Solutions › Codeforces Beta Round 30 (Codeforces format) ›

CF 30A - Accounting

We are given three integers, A, B, and n. The task is to find an integer value X such that:
codeforces competitive-programming brute-force math May 28, 2026
Practice › Codeforces Solutions › Codeforces Beta Round 30 (Codeforces format) ›

CF 30B - Codeforces World Finals

We are given two dates in the format DD.MM.YY: one representing the day of the Codeforces World Finals and the other representing Bob's date of birth. Bob can rearrange the components of his birth date-the day, month, and year-but only as complete numbers, not individual digits.
codeforces competitive-programming implementation May 28, 2026
Practice › Codeforces Solutions › Codeforces Beta Round 30 (Codeforces format) ›

CF 30C - Shooting Gallery

We are asked to help King Copa maximize his expected number of hits in a shooting gallery. The gallery is represented as a 2D plane, and each target appears at a specific point exactly at a specific time and disappears immediately afterward.
codeforces competitive-programming dp probabilities May 28, 2026
Practice › Codeforces Solutions › Codeforces Beta Round 30 (Codeforces format) ›

CF 30D - King's Problem?

We have n + 1 cities. The first n cities lie on the x-axis at positions (x1, 0), (x2, 0), ..., (xn, 0). One additional city is somewhere off the axis at (x_{n+1}, y_{n+1}).
codeforces competitive-programming geometry greedy May 28, 2026
Practice › Codeforces Solutions › Codeforces Beta Round 30 (Codeforces format) ›

CF 30E - Tricky and Clever Password

We are given a single lowercase string. Somewhere inside this string, there exists a hidden palindrome of odd length, but the palindrome was split into three consecutive parts:
codeforces competitive-programming binary-search constructive-algorithms data-structures greedy hashing strings May 28, 2026