Educational Codeforces Round 149 (Rated for Div. 2)

Solutions for Educational Codeforces Round 149 (Rated for Div. 2) (contest 1837). 1/6 problems verified against sample I/O. Difficulty range: 800-2400.

6 items

Educational Codeforces Round 149 (Rated for Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 1/6 | Rating range: 800-2400 | Time: 10m 40s

Problem Name Rating Tags Solve Time Verified
A Grasshopper on a Line 800 constructive-algorithms, math 2m ✗
B Comparison String 900 greedy 1m 21s ✗
C Best Binary String 1000 constructive-algorithms, greedy 1m 38s ✗
D Bracket Coloring 1400 constructive-algorithms, greedy 1m 31s ✗
E Playoff Fixing 2200 combinatorics, trees 1m 32s ✓
F Editorial for Two 2400 binary-search, data-structures, greedy 2m 38s ✗
Practice › Codeforces Solutions › Educational Codeforces Round 149 (Rated for Div. 2) ›

CF 1837F - Editorial for Two

The error you are seeing, StopIteration, happens because the code is trying to consume more integers from the input iterator than exist.
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Practice › Codeforces Solutions › Educational Codeforces Round 149 (Rated for Div. 2) ›

CF 1837E - Playoff Fixing

We are asked to arrange a single-elimination tournament for $2^k$ teams where each team has a strict ranking: team 1 is the strongest, team $2^k$ is the weakest, and a stronger team always beats a weaker one.
codeforces competitive-programming combinatorics trees Jun 9, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 149 (Rated for Div. 2) ›

CF 1837D - Bracket Coloring

We are given a string of parentheses and we are asked to color each parenthesis with a number such that, for each color, the subsequence of parentheses using only that color forms a beautiful bracket sequence.
codeforces competitive-programming constructive-algorithms greedy Jun 9, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 149 (Rated for Div. 2) ›

CF 1837A - Grasshopper on a Line

Ah, now the bug is clear. Simply taking the maximum of the final list is not correct, because the largest number in the final list may be generated by the difference operation and might not be one of the original two numbers.
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Practice › Codeforces Solutions › Educational Codeforces Round 149 (Rated for Div. 2) ›

CF 1837C - Best Binary String

We are given a string s that contains 0, 1, and ?. The question marks represent flexible positions: we can replace each ? independently with either 0 or 1. Our goal is to produce a fully binary string matching this pattern such that the cost of sorting it is minimized.
codeforces competitive-programming constructive-algorithms greedy Jun 9, 2026
Practice › Codeforces Solutions › Educational Codeforces Round 149 (Rated for Div. 2) ›

CF 1837B - Comparison String

We are given a string that encodes local comparisons between neighboring elements of an array. Each character describes whether the next element must be larger or smaller than the current one.
codeforces competitive-programming greedy Jun 9, 2026