Educational Codeforces Round 118 (Rated for Div. 2)

Solutions for Educational Codeforces Round 118 (Rated for Div. 2) (contest 1613). 3/6 problems verified against sample I/O. Difficulty range: 900-2600.

6 items

Educational Codeforces Round 118 (Rated for Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 3/6 | Rating range: 900-2600 | Time: 8m 38s

Problem Name Rating Tags Solve Time Verified
A Long Comparison 900 implementation, math 1m 19s ✓
B Absent Remainder 1000 greedy, implementation, sortings 1m 41s ✗
C Poisoned Dagger 1200 binary-search 1m 14s ✓
D MEX Sequences 1900 dp, math 1m 23s ✗
E Crazy Robot 2000 dfs-and-similar, graphs 1m 12s ✓
F Tree Coloring 2600 combinatorics, divide-and-conquer, fft 1m 49s ✗
Practice › Codeforces Solutions › Educational Codeforces Round 118 (Rated for Div. 2) ›

CF 1613F - Tree Coloring

We are given a rooted tree where vertex 1 is fixed as the root. The task is to assign a distinct label from 1 to n to every vertex, so the labels form a permutation of 1 to n.
codeforces competitive-programming combinatorics divide-and-conquer fft Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 118 (Rated for Div. 2) ›

CF 1613D - MEX Sequences

We are asked to count subsequences of an array where every prefix of the subsequence behaves in a very specific “MEX-stable” way.
codeforces competitive-programming dp math Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 118 (Rated for Div. 2) ›

CF 1613E - Crazy Robot

We are given a rectangular grid of size n × m containing three types of cells: free cells, blocked cells, and a single lab. The robot can occupy any free cell, and at each step we can issue one of four commands: move up, down, left, or right.
codeforces competitive-programming dfs-and-similar graphs Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 118 (Rated for Div. 2) ›

CF 1613B - Absent Remainder

We are given a sequence of distinct positive integers. Our task is to construct roughly half as many pairs of numbers as the length of the sequence, where for each pair $(x, y)$, both numbers come from the sequence, they are distinct, and the remainder when $x$ is divided by…
codeforces competitive-programming greedy implementation sortings Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 118 (Rated for Div. 2) ›

CF 1613A - Long Comparison

Each number in this problem is not given in its expanded form, but as a compact description. Instead of writing the full integer, we are given a base value x and a number of trailing zeros p, meaning the actual number is x × 10^p.
codeforces competitive-programming implementation math Jun 10, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 118 (Rated for Div. 2) ›

CF 1613C - Poisoned Dagger

We are given a sequence of attack times and a dragon with h hit points. Each attack applies a poison that lasts k seconds and deals 1 damage per second. If the dragon is already poisoned when a new attack lands, the poison timer resets.
codeforces competitive-programming binary-search Jun 10, 2026