Pinely Round 3 (Div. 1 + Div. 2)

Solutions for Pinely Round 3 (Div. 1 + Div. 2) (contest 1909). 4/10 problems verified against sample I/O. Difficulty range: 800-3500.

10 items

Pinely Round 3 (Div. 1 + Div. 2)

Type: Div. 1+2 | Problems: 10 | Verified: 4/10 | Rating range: 800-3500 | Time: 19m 20s

Problem Name Rating Tags Solve Time Verified
A Distinct Buttons 800 implementation, math 1m 36s ✓
B Make Almost Equal With Mod 1200 bitmasks, constructive-algorithms, math 2m 6s ✗
C Heavy Intervals 1400 constructive-algorithms, data-structures, dsu 1m 55s ✓
D Split Plus K 1900 greedy, math, number-theory 1m 59s ✓
E Multiple Lamps 2400 bitmasks, brute-force, constructive-algorithms 2m 14s ✗
F1 Small Permutation Problem (Easy Version) 2200 brute-force, combinatorics, dp 46s ✗
F2 Small Permutation Problem (Hard Version) 2500 combinatorics, dp, math 2m 31s ✗
G Pumping Lemma 3000 hashing, strings 1m 22s ✓
H Parallel Swaps Sort 3500 constructive-algorithms, data-structures 1m 52s ✗
I Short Permutation Problem 1900 combinatorics, dp, fft 2m 59s ✗
Practice › Codeforces Solutions › Pinely Round 3 (Div. 1 + Div. 2) ›

CF 1909I - Short Permutation Problem

We are asked to count permutations of the numbers from 1 to $n$ with a specific property: for each possible threshold $m$ between 3 and $n+1$, and for each count $k$ between 0 and $n-1$, we need the number of permutations where exactly $k$ consecutive pairs $(pi, p{i+1})$…
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CF 1909H - Parallel Swaps Sort

We are given a permutation of the integers from 1 to $n$. The task is to sort this permutation into increasing order using a very specific operation: we select a subarray of even length, then perform swaps in adjacent pairs throughout that subarray.
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CF 1909F2 - Small Permutation Problem (Hard Version)

For every position $i$, look at the prefix $p1,dots,pi$ of a permutation. Define $$f(i)={jle i mid pjle i}.$$ Some positions contain a prescribed value $ai$, meaning $f(i)$ must be exactly $ai$. Positions with $ai=-1$ impose no restriction.
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CF 1909G - Pumping Lemma

We are given two strings, s of length n and t of length m, where n is strictly smaller than m. The task is to count the number of ways we can split s into three contiguous substrings x, y, z such that when we take x, repeat y some number of times (at least once), and then…
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CF 1909E - Multiple Lamps

Each test gives a set of switches, where switch $i$ toggles all lamps whose indices are multiples of $i$. Turning a switch an odd number of times matters, but here each switch can be pressed at most once, so each chosen switch contributes exactly one toggle operation.
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CF 1909D - Split Plus K

We are given a multiset of positive integers and a number $k$. We can repeatedly choose any number $x$ on the blackboard, erase it, and replace it with two positive integers $y$ and $z$ such that $y + z = x + k$.
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CF 1909F1 - Small Permutation Problem (Easy Version)

Working
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CF 1909B - Make Almost Equal With Mod

We are given an array of distinct positive integers. The task is to choose a positive integer k such that when every element of the array is replaced by its remainder modulo k, the resulting array contains exactly two distinct values.
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CF 1909C - Heavy Intervals

We are given a set of $n$ intervals on the number line. Each interval has a left endpoint $li$, a right endpoint $ri$, and a weight per unit length $ci$. The actual weight of an interval is calculated as $ci cdot (ri - li)$.
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CF 1909A - Distinct Buttons

We are asked to move on an infinite grid starting from the origin. We have four possible moves corresponding to the four cardinal directions: up, down, left, and right.
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