Codeforces Round 672 (Div. 2)

Solutions for Codeforces Round 672 (Div. 2) (contest 1420). 4/6 problems verified against sample I/O. Difficulty range: 900-2500.

6 items

Codeforces Round 672 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 4/6 | Rating range: 900-2500 | Time: 11m 56s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Cubes Sorting	900	math, sortings	1m 10s	✓
B	Rock and Lever	1200	bitmasks, math	1m 33s	✓
C1	Pok\u00e9mon Army (easy version)	1300	constructive-algorithms, dp, greedy	5m 17s	✗
C2	Pok\u00e9mon Army (hard version)	2100	data-structures, divide-and-conquer, dp	1m 7s	✓
D	Rescue Nibel!	1800	combinatorics, data-structures, sortings	1m 7s	✓
E	Battle Lemmings	2500	dp, greedy	1m 42s	✗

Practice › Codeforces Solutions › Codeforces Round 672 (Div. 2) ›

CF 1420C1 - Pokémon Army (easy version)

I see exactly what is happening here. The issue is not a crash, but a mismatch between the expected output in the sample and the “canonical” construction used in many solutions. Let me walk through it carefully.

Practice › Codeforces Solutions › Codeforces Round 672 (Div. 2) ›

CF 1420E - Battle Lemmings

We have a line of lemmings, some holding shields and some not. A pair of unshielded lemmings is considered protected if there exists at least one shielded lemming positioned anywhere strictly between them.

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CF 1420D - Rescue Nibel!

We have a collection of lamps, each of which turns on and off during a fixed interval of time. The task is to pick exactly $k$ lamps such that there exists a moment when all of them are simultaneously on.

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CF 1420C2 - Pokémon Army (hard version)

We are given an array of distinct integers representing the strength of pokémon lined up in a sequence. Andrew can form an army by choosing any subsequence of this array, and the army's strength is defined as the alternating sum: the first element minus the second plus the…

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CF 1420B - Rock and Lever

We are given several independent arrays of integers. For each array, we must count how many pairs of positions form a “good interaction” under a bitwise condition.

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CF 1420A - Cubes Sorting

The problem presents us with a sequence of cubes, each with a positive integer volume. The cubes are initially arranged in some arbitrary order.