Educational Codeforces Round 108 (Rated for Div. 2)

Solutions for Educational Codeforces Round 108 (Rated for Div. 2) (contest 1519). 1/6 problems verified against sample I/O. Difficulty range: 800-3200.

6 items

Educational Codeforces Round 108 (Rated for Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 1/6 | Rating range: 800-3200 | Time: 12m 19s

Problem Name Rating Tags Solve Time Verified
A Red and Blue Beans 800 math 59s ✗
B The Cake Is a Lie 800 dp, math 1m 2s ✗
C Berland Regional 1400 brute-force, data-structures, greedy 2m 59s ✗
D Maximum Sum of Products 1600 brute-force, dp, implementation 2m 4s ✓
E Off by One 2700 constructive-algorithms, dfs-and-similar, geometry 2m 32s ✗
F Chests and Keys 3200 bitmasks, brute-force, dfs-and-similar 2m 43s ✗
Practice › Codeforces Solutions › Educational Codeforces Round 108 (Rated for Div. 2) ›

CF 1519F - Chests and Keys

Method 1b already provides the key idea. If $(umldots u1u0)3$ is a ternary integer, its decimal value is obtained from the nested form $$(cdots((umcdot3+u{m-1})cdot3+u{m-2})cdots)cdot3+u0.$$ For pencil-and-paper work this means: Start with the leading digit.
codeforces competitive-programming bitmasks brute-force dfs-and-similar dp flows Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 108 (Rated for Div. 2) ›

CF 1519E - Off by One

We are given $n$ points in the first quadrant of a plane. Each point is defined by a pair of rational coordinates $(xi, yi)$, where $xi = ai / bi$ and $yi = ci / di$.
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Practice › Codeforces Solutions › Educational Codeforces Round 108 (Rated for Div. 2) ›

CF 1519D - Maximum Sum of Products

We are given two arrays of integers, a and b, both of the same length n. The task is to maximize the sum of element-wise products, $sum ai cdot bi$, by reversing at most one contiguous subarray of a.
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Practice › Codeforces Solutions › Educational Codeforces Round 108 (Rated for Div. 2) ›

CF 1519C - Berland Regional

Method 1b already provides the key idea. If $(umldots u1u0)3$ is a ternary integer, its decimal value is obtained from the nested form $$(cdots((umcdot3+u{m-1})cdot3+u{m-2})cdots)cdot3+u0.$$ For pencil-and-paper work this means: Start with the leading digit.
codeforces competitive-programming brute-force data-structures greedy number-theory sortings Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 108 (Rated for Div. 2) ›

CF 1519B - The Cake Is a Lie

We are given a rectangular grid with n rows and m columns. You start at the top-left corner (1, 1) and want to reach the bottom-right corner (n, m) by only moving right or down. Moving right from cell (x, y) costs x burles, moving down costs y burles.
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Practice › Codeforces Solutions › Educational Codeforces Round 108 (Rated for Div. 2) ›

CF 1519A - Red and Blue Beans

We have two colors of beans, red and blue. Every packet we create must contain at least one bean of each color, and inside any packet the difference between the number of red and blue beans cannot exceed d. The question is whether all
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