Codeforces Round 1047 (Div. 3)

7 problems from Codeforces Round 1047 (Div. 3) (contest 2137), difficulty 800-2200. 1/7 solutions verified against sample I/O.

7 items

Codeforces Round 1047 (Div. 3)

Div. 3 | 7 problems | 1/7 verified | Difficulty 800-2200 | 13m 16s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Collatz Conjecture	800	constructive-algorithms, math	35,295	1m 59s
B	Fun Permutation	900	constructive-algorithms, math, number-theory	26,450	1m 28s
C	Maximum Even Sum	1100	brute-force, greedy, implementation	22,896	1m 55s
D	Replace with Occurrences	1200	constructive-algorithms	19,525	3m 4s
E	Mexification	1500	brute-force, implementation, math	10,157	1m 39s
F	Prefix Maximum Invariance	1900	binary-search, combinatorics, data-structures	4,055	1m 42s	✓
G	Cry Me a River	2200	dfs-and-similar, dp, games	1,931	1m 29s

Practice › Codeforces Solutions › Codeforces Round 1047 (Div. 3) ›

CF 2137G - Cry Me a River

We are given a directed acyclic graph with n nodes and m edges. Each node starts colored blue, and players Cry and River play a two-player token game. The token starts at a node s. Cry moves first, then River, and they alternate.

Practice › Codeforces Solutions › Codeforces Round 1047 (Div. 3) ›

CF 2137D - Replace with Occurrences

We are given a sequence of numbers, and we want to interpret each number in that sequence as a frequency requirement for some unknown array we must construct.

Practice › Codeforces Solutions › Codeforces Round 1047 (Div. 3) ›

CF 2137F - Prefix Maximum Invariance

For any array $x$, its sequence of prefix maxima is completely determined. At position $i$, the prefix maximum is $$max(x1,x2,dots,xi).$$ We are allowed to build another array $z$ whose prefix maxima are identical to those of $x$.

Practice › Codeforces Solutions › Codeforces Round 1047 (Div. 3) ›

CF 2137E - Mexification

We are given an array of integers and asked to perform a special transformation multiple times. For each element in the array, we replace it with the minimum non-negative integer that does not appear anywhere else in the array.

Practice › Codeforces Solutions › Codeforces Round 1047 (Div. 3) ›

CF 2137A - Collatz Conjecture

We are given the result of running the Collatz operation exactly k times and the final value x. The task is not to find the original value uniquely, because many different starting values may lead to the same result.

Practice › Codeforces Solutions › Codeforces Round 1047 (Div. 3) ›

CF 2137C - Maximum Even Sum

We are given two integers, $a$ and $b$, and we can pick a positive integer $k$ such that $b$ is divisible by $k$. Then we replace $a$ with $a cdot k$ and $b$ with $b / k$. The goal is to make the sum $a + b$ as large as possible while ensuring it is even.

Practice › Codeforces Solutions › Codeforces Round 1047 (Div. 3) ›

CF 2137B - Fun Permutation

We are given a permutation $p$ of size $n$, meaning it contains each integer from $1$ to $n$ exactly once. We must construct another permutation $q$ of the same size, also a rearrangement of $1$ to $n$, with a structural constraint linking adjacent positions.