Educational Codeforces Round 127 (Rated for Div. 2)

Solutions for Educational Codeforces Round 127 (Rated for Div. 2) (contest 1671). 3/6 problems verified against sample I/O. Difficulty range: 800-2700.

6 items

Educational Codeforces Round 127 (Rated for Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 3/6 | Rating range: 800-2700 | Time: 13m 7s

Problem Name Rating Tags Solve Time Verified
A String Building 800 implementation 3m 36s ✓
B Consecutive Points Segment 1000 brute-force, math, sortings 2m ✓
C Dolce Vita 1200 binary-search, brute-force, greedy 1m 55s ✗
D Insert a Progression 1600 brute-force, constructive-algorithms, greedy 1m 48s ✗
E Preorder 2100 combinatorics, divide-and-conquer, dp 1m 26s ✓
F Permutation Counting 2700 brute-force, combinatorics, dp 2m 22s ✗
Practice › Codeforces Solutions › Educational Codeforces Round 127 (Rated for Div. 2) ›

CF 1671F - Permutation Counting

We are counting permutations of size $n$ with two simultaneous structural constraints. The first constraint fixes the total number of inversions, meaning how many pairs $(i, j)$ with $i < j$ appear in reversed order in the permutation.
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Practice › Codeforces Solutions › Educational Codeforces Round 127 (Rated for Div. 2) ›

CF 1671D - Insert a Progression

We are given an array of integers a and a set of extra integers {1, 2, …, x}. The task is to insert all these extra integers into a in any order and at any positions, including at the beginning or end.
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Practice › Codeforces Solutions › Educational Codeforces Round 127 (Rated for Div. 2) ›

CF 1671A - String Building

The input to the system is well-formed but the observed failure pattern is not a mathematical or logical inconsistency of the task; it is a structural defect: the program produces no output at all for multiple independent test cases, indicating that the core loop does not…
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CF 1671E - Preorder

We are given a complete binary tree of size $2^n - 1$, where every internal node has exactly two children and all leaves lie on the same level. Each node carries a label, either A or B.
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Practice › Codeforces Solutions › Educational Codeforces Round 127 (Rated for Div. 2) ›

CF 1671B - Consecutive Points Segment

We are given a set of points on a number line, already sorted in increasing order. Each point is allowed to “wiggle” by at most one unit, meaning its final position can be its original coordinate, one step left, or one step right.
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Practice › Codeforces Solutions › Educational Codeforces Round 127 (Rated for Div. 2) ›

CF 1671C - Dolce Vita

We have a scenario where you want to buy sugar packs from several shops over consecutive days, with each shop selling one pack per day. Each shop has an initial price for its pack, and every day the price increases by one.
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