Codeforces Round 1051 (Div. 2)

7 problems from Codeforces Round 1051 (Div. 2) (contest 2143), difficulty 800-2700. 1/7 solutions verified against sample I/O.

7 items

Codeforces Round 1051 (Div. 2)

Div. 2 | 7 problems | 1/7 verified | Difficulty 800-2700 | 13m 38s

#	Problem	Rating	Tags	Accepted	Time	✓
A	All Lengths Subtraction	800	brute-force, two-pointers	20,693	2m 15s	✓
B	Discounts	1000	greedy, sortings, two-pointers	20,903	1m 47s
C	Max Tree	1300	constructive-algorithms, dfs-and-similar, graphs	14,091	1m 41s
D1	Inversion Graph Coloring (Easy Version)	1800	combinatorics, data-structures, dp	6,393	1m 55s
D2	Inversion Graph Coloring (Hard Version)	2200	binary-search, combinatorics, data-structures	2,769	3m 6s
E	Make Good	2400	constructive-algorithms, greedy, math	1,918	1m 27s
F	Increasing Xor	2700	bitmasks, data-structures, math	423	1m 27s

Practice › Codeforces Solutions › Codeforces Round 1051 (Div. 2) ›

CF 2143F - Increasing Xor

We are given an array of small integers, and we are allowed to repeatedly pick two positions inside a chosen segment and XOR the value at the later index with the value at the earlier index.

Practice › Codeforces Solutions › Codeforces Round 1051 (Div. 2) ›

CF 2143D2 - Inversion Graph Coloring (Hard Version)

We are given a sequence of integers and asked to count how many of its subsequences can be colored in red and blue such that, for every inversion (a pair of indices $i < j$ with $ai aj$), the two elements have different colors.

Practice › Codeforces Solutions › Codeforces Round 1051 (Div. 2) ›

CF 2143E - Make Good

We start with a string made only of opening and closing brackets. The string is not fixed: we are allowed to repeatedly pick two adjacent identical brackets and flip them as a pair.

Practice › Codeforces Solutions › Codeforces Round 1051 (Div. 2) ›

CF 2143D1 - Inversion Graph Coloring (Easy Version)

We are given a sequence of integers, each between 1 and n, and we want to count subsequences that can be “colored” red or blue in such a way that every inversion in the subsequence has endpoints of different colors.

Practice › Codeforces Solutions › Codeforces Round 1051 (Div. 2) ›

CF 2143A - All Lengths Subtraction

We are given a permutation of length $n$, which is an array containing all integers from 1 to $n$ in some order, with no duplicates. We must perform a series of exactly $n$ operations, one for each $k$ from 1 to $n$.

Practice › Codeforces Solutions › Codeforces Round 1051 (Div. 2) ›

CF 2143B - Discounts

We are asked to buy a set of products with individual prices while minimizing the total cost using discount vouchers. Each voucher allows you to pick a fixed number of products and get the cheapest among them for free.

Practice › Codeforces Solutions › Codeforces Round 1051 (Div. 2) ›

CF 2143C - Max Tree

We are given a tree with n vertices and n-1 edges, each edge carrying two non-negative integers x and y. The problem asks us to assign distinct integers from 1 to n to the vertices so that the sum of edge contributions is maximized.