Codeforces Round 837 (Div. 2)

Solutions for Codeforces Round 837 (Div. 2) (contest 1771). 2/6 problems verified against sample I/O. Difficulty range: 900-2500.

6 items

Codeforces Round 837 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 2/6 | Rating range: 900-2500 | Time: 11m 34s

Problem Name Rating Tags Solve Time Verified
A Hossam and Combinatorics 900 combinatorics, math, sortings 1m 7s ✓
B Hossam and Friends 1400 binary-search, constructive-algorithms, dp 2m 26s ✗
C Hossam and Trainees 1600 greedy, math, number-theory 2m 12s ✗
D Hossam and (sub-)palindromic tree 2100 brute-force, data-structures, dfs-and-similar 2m ✗
E Hossam and a Letter 2500 brute-force, dp, implementation 1m 32s ✓
F Hossam and Range Minimum Query 2500 binary-search, bitmasks, data-structures 2m 17s ✗
Practice › Codeforces Solutions › Codeforces Round 837 (Div. 2) ›

CF 1771D - Hossam and (sub-)palindromic tree

We are given a tree with $n$ vertices, each labeled with a lowercase English letter. For any two vertices $v$ and $u$, define the string $s(v,u)$ as the sequence of letters along the unique path connecting them.
codeforces competitive-programming brute-force data-structures dfs-and-similar dp strings trees Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 837 (Div. 2) ›

CF 1771F - Hossam and Range Minimum Query

This is a Type B (prove inequality) problem, not Type C. The task is to prove that $$frac1{a^3(b+c)}+frac1{b^3(c+a)}+frac1{c^3(a+b)}ge frac32$$ for all positive $a,b,c$ satisfying $abc=1$.
codeforces competitive-programming binary-search bitmasks data-structures hashing probabilities strings trees Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 837 (Div. 2) ›

CF 1771E - Hossam and a Letter

We are given an n × m grid representing Hossam's ground. Each cell has a quality: perfect (.), medium (m), or bad (). Hossam wants to draw the letter 'H' by placing walls on some cells. The letter consists of two vertical lines and one horizontal line connecting them.
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Practice › Codeforces Solutions › Codeforces Round 837 (Div. 2) ›

CF 1771B - Hossam and Friends

This is a Type B (prove inequality) problem, not Type C. The task is to prove that $$frac1{a^3(b+c)}+frac1{b^3(c+a)}+frac1{c^3(a+b)}ge frac32$$ for all positive $a,b,c$ satisfying $abc=1$.
codeforces competitive-programming binary-search constructive-algorithms dp two-pointers Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 837 (Div. 2) ›

CF 1771C - Hossam and Trainees

This is a Type C (optimization) problem. The requirements are to establish an upper bound on the boundary length $L$ between horizontal and vertical dominoes and to exhibit a construction that achieves the maximal possible $L$.
codeforces competitive-programming greedy math number-theory Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 837 (Div. 2) ›

CF 1771A - Hossam and Combinatorics

We are given an array for each test case, and we are asked to focus only on pairs of positions in that array. From every ordered pair of distinct indices, we can compute the absolute difference between the two values.
codeforces competitive-programming combinatorics math sortings Jun 9, 2026