Educational Codeforces Round 125 (Rated for Div. 2)

Solutions for Educational Codeforces Round 125 (Rated for Div. 2) (contest 1657). 4/6 problems verified against sample I/O. Difficulty range: 800-2600.

6 items

Educational Codeforces Round 125 (Rated for Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 4/6 | Rating range: 800-2600 | Time: 12m 30s

Problem Name Rating Tags Solve Time Verified
A Integer Moves 800 brute-force, math 1m 39s ✓
B XY Sequence 800 greedy 1m 56s ✓
C Bracket Sequence Deletion 1200 greedy, implementation 4m 11s ✗
D For Gamers. By Gamers. 2000 binary-search, brute-force, greedy 1m 1s ✓
E Star MST 2200 combinatorics, dp, graph-matchings 2m 4s ✓
F Words on Tree 2600 2-sat, dfs-and-similar, dsu 1m 39s ✗
Practice › Codeforces Solutions › Educational Codeforces Round 125 (Rated for Div. 2) ›

CF 1657F - Words on Tree

We are asked to label the vertices of a tree with lowercase letters so that a set of path constraints is satisfied.
codeforces competitive-programming 2-sat dfs-and-similar dsu graphs trees Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 125 (Rated for Div. 2) ›

CF 1657C - Bracket Sequence Deletion

The task is to repeatedly remove "good" prefixes from a bracket string. A prefix is good if it is either a regular bracket sequence or a palindrome of length at least two.
codeforces competitive-programming greedy implementation Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 125 (Rated for Div. 2) ›

CF 1657E - Star MST

We have a complete graph on n labeled vertices. Every edge receives an integer weight between 1 and k. Vertex 1 plays a special role. Consider the star centered at vertex 1, consisting of all edges (1, v) for v 1.
codeforces competitive-programming combinatorics dp graph-matchings math Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 125 (Rated for Div. 2) ›

CF 1657D - For Gamers. By Gamers.

We have a strategy game scenario where Monocarp recruits a squad to fight a sequence of monsters. Each battle starts with an empty squad, and Monocarp can spend up to C coins per battle. Each unit type has a cost, damage per second, and health.
codeforces competitive-programming binary-search brute-force greedy math sortings Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 125 (Rated for Div. 2) ›

CF 1657B - XY Sequence

We need to construct an array $a0, a1, dots, an$ starting from $a0 = 0$. For every next position, we have exactly two choices. We can either increase the current value by $x$, or decrease it by $y$. The only restriction is that every value in the sequence must stay at most $B$.
codeforces competitive-programming greedy Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 125 (Rated for Div. 2) ›

CF 1657A - Integer Moves

We start with a chip at the origin (0, 0) and want to reach a target point (x, y). A move is allowed whenever the Euclidean distance between the current position and the next position is an integer. The task is to find the minimum number of moves needed to reach the target.
codeforces competitive-programming brute-force math Jun 10, 2026