Educational Codeforces Round 106 (Rated for Div. 2)

7 problems from Educational Codeforces Round 106 (Rated for Div. 2) (contest 1499), difficulty 800-3100. 5/7 solutions verified against sample I/O.

7 items

Educational Codeforces Round 106 (Rated for Div. 2)

Div. 2 | 7 problems | 5/7 verified | Difficulty 800-3100 | 30m 33s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Domino on Windowsill	800	combinatorics, constructive-algorithms, math	21,967	4m 30s	✓
B	Binary Removals	1000	brute-force, dp, greedy	22,007	3m 1s	✓
C	Minimum Grid Path	1500	brute-force, data-structures, greedy	13,417	4m 4s	✓
D	The Number of Pairs	2100	dp, math, number-theory	7,039	5m 6s	✓
E	Chaotic Merge	2400	combinatorics, dp, math	1,662	4m 19s
F	Diameter Cuts	2400	combinatorics, dfs-and-similar, dp	1,588	3m 41s	✓
G	Graph Coloring	3100	data-structures, graphs, interactive	237	5m 52s

Practice › Codeforces Solutions › Educational Codeforces Round 106 (Rated for Div. 2) ›

CF 1499G - Graph Coloring

We start with a bipartite graph whose edges arrive online. Each edge must eventually be assigned one of two labels, red or blue. For any vertex, we compare how many incident edges are red versus blue, and we pay the absolute difference of these two counts.

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CF 1499F - Diameter Cuts

We are working with a tree where every edge is initially present. We are allowed to remove any subset of edges, which splits the tree into several connected components. Each resulting component is still a tree.

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CF 1499E - Chaotic Merge

We are given two strings, and we imagine taking substrings from each of them and interleaving their characters while preserving internal order inside each substring.

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CF 1499D - The Number of Pairs

We are asked to count how many ordered pairs of positive integers $(a, b)$ satisfy a single arithmetic constraint that mixes their least common multiple and greatest common divisor.

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CF 1499C - Minimum Grid Path

We are constructing a monotone path from the bottom-left corner of a grid to the top-right corner, but the path is not just a simple sequence of unit steps.

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CF 1499B - Binary Removals

We are given a binary string and we are allowed to delete characters, but with a constraint: any deleted positions must not be adjacent in the original string. After deleting some chosen characters, we concatenate the remaining ones and obtain a shorter string.

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CF 1499A - Domino on Windowsill

We are given a board of size $2 times n$, where the first $k1$ cells of the top row and $k2$ cells of the bottom row are white, and the rest are black. We are also given a number of white dominoes $w$ and black dominoes $b$.