Codeforces Round 728 (Div. 1)

Solutions for Codeforces Round 728 (Div. 1) (contest 1540). 0/6 problems verified against sample I/O. Difficulty range: 1400-3500.

6 items

Codeforces Round 728 (Div. 1)

Type: Div. 1 | Problems: 6 | Verified: 0/6 | Rating range: 1400-3500 | Time: 33m 39s

Problem Name Rating Tags Solve Time Verified
A Great Graphs 1400 constructive-algorithms, graphs, greedy 3m 14s ✗
B Tree Array 2300 brute-force, combinatorics, dp 4m 3s ✗
C1 Converging Array (Easy Version) 2700 dp, math 8m 35s ✗
C2 Converging Array (Hard Version) 2900 dp, math 2m 33s ✗
D Inverse Inversions 3200 binary-search, brute-force, data-structures 8m 43s ✗
E Tasty Dishes 3500 math, matrices 6m 31s ✗
Practice › Codeforces Solutions › Codeforces Round 728 (Div. 1) ›

Practice › Codeforces Solutions › Codeforces Round 728 (Div. 1) ›

CF 1540D - Inverse Inversions

The array $b$ is not arbitrary. For every position $i$, $bi$ tells us how many earlier elements of the permutation are larger than $pi$.
codeforces competitive-programming binary-search brute-force data-structures Jun 10, 2026
Practice › Codeforces Solutions › Codeforces Round 728 (Div. 1) ›

CF 1540E - Tasty Dishes

We are given a small directed system of chefs, where each chef holds a value. The structure is acyclic in the sense that chef $i$ can only interact with chefs of higher index. This allows information to flow only from right to left.
codeforces competitive-programming math matrices Jun 10, 2026
Practice › Codeforces Solutions › Codeforces Round 728 (Div. 1) ›

CF 1540C1 - Converging Array (Easy Version)

The operation acts on a neighboring pair. Let $$di=a{i+1}-ai.$$ If $dige bi$, the operation changes nothing. If $di<bi$, both values are replaced by numbers with the same sum and with difference exactly $bi$.
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CF 1540B - Tree Array

We are asked to calculate the expected number of inversions in a random process of marking nodes in a tree. The tree has n nodes, and the marking process begins with a uniformly random initial node.
codeforces competitive-programming brute-force combinatorics dp graphs math probabilities trees Jun 10, 2026
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CF 1540A - Great Graphs

We are given a farm with $n$ pastures and one-way roads between them. Each road has a travel time, which can be negative. Farmer John remembers only the shortest travel times from pasture 1 to every other pasture.
codeforces competitive-programming constructive-algorithms graphs greedy shortest-paths sortings Jun 10, 2026