Codeforces Round 960 (Div. 2)

Solutions for Codeforces Round 960 (Div. 2) (contest 1990). 1/7 problems verified against sample I/O. Difficulty range: 900-2800.

7 items

Codeforces Round 960 (Div. 2)

Type: Div. 2 | Problems: 7 | Verified: 1/7 | Rating range: 900-2800 | Time: 18m 31s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Submission Bait	900	brute-force, games, greedy	3m 55s	✗
B	Array Craft	1200	constructive-algorithms, greedy	2m 33s	✗
C	Mad MAD Sum	1500	brute-force, greedy, math	2m 48s	✓
D	Grid Puzzle	1800	bitmasks, brute-force, dp	2m 13s	✗
E1	Catch the Mole(Easy Version)	2500	binary-search, data-structures, dfs-and-similar	2m 4s	✗
E2	Catch the Mole(Hard Version)	2600	binary-search, data-structures, dfs-and-similar	2m 21s	✗
F	Polygonal Segments	2800	brute-force, data-structures, divide-and-conquer	2m 37s	✗

Practice › Codeforces Solutions › Codeforces Round 960 (Div. 2) ›

CF 1990F - Polygonal Segments

We are given a dynamic array of positive values, and we repeatedly modify it while also answering range queries. The interesting object is a subarray that behaves like the side lengths of a polygon.

Practice › Codeforces Solutions › Codeforces Round 960 (Div. 2) ›

CF 1990E2 - Catch the Mole(Hard Version)

We are working with a rooted tree where node 1 is fixed as the root. Somewhere in this tree there is a hidden token, called the mole, which occupies a single node. We do not know its position initially, but we can interact with the system by querying any node x.

Practice › Codeforces Solutions › Codeforces Round 960 (Div. 2) ›

CF 1990E1 - Catch the Mole(Easy Version)

We are working with a rooted tree where node 1 is the root, and one hidden token, the “mole”, starts at some unknown node. We cannot observe its position directly. Instead, we interact with the tree using queries on nodes.

Practice › Codeforces Solutions › Codeforces Round 960 (Div. 2) ›

CF 1990D - Grid Puzzle

We are given a one-dimensional array of integers, where each integer represents how many consecutive cells in a row of a grid are initially black.

Practice › Codeforces Solutions › Codeforces Round 960 (Div. 2) ›

CF 1990A - Submission Bait

We have a two-player game on an array of integers. Alice and Bob take turns, with Alice starting first. Initially, a variable mx is zero. On their turn, a player can choose an array element a[i] if it is at least mx, set mx to that value, and then set a[i] to zero.

Practice › Codeforces Solutions › Codeforces Round 960 (Div. 2) ›

CF 1990C - Mad MAD Sum

We are given an array of integers, and we need to repeatedly update it while accumulating a running sum. The update rule is based on the concept of $operatorname{MAD}$ - the maximum number that appears at least twice in a prefix of the array.

Practice › Codeforces Solutions › Codeforces Round 960 (Div. 2) ›

CF 1990B - Array Craft

We need to construct an array of length $n$, where each element is either $+1$ or $-1$. Two special positions are defined based on prefix sums and suffix sums. For prefixes, we look at all partial sums $Si = a1 + dots + ai$.