Codeforces Round 691 (Div. 1)

Solutions for Codeforces Round 691 (Div. 1) (contest 1458). 2/6 problems verified against sample I/O. Difficulty range: 1600-3500.

6 items

Codeforces Round 691 (Div. 1)

Type: Div. 1 | Problems: 6 | Verified: 2/6 | Rating range: 1600-3500 | Time: 22m 51s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Row GCD	1600	math, number-theory	4m 24s	✓
B	Glass Half Spilled	2000	dp	2m 10s	✓
C	Latin Square	2700	math, matrices	5m 56s	✗
D	Flip and Reverse	3100	data-structures, graphs, greedy	2m 3s	✗
E	Nim Shortcuts	3100	data-structures, games	1m 49s	✗
F	Range Diameter Sum	3500	data-structures, trees	6m 29s	✗

Practice › Codeforces Solutions › Codeforces Round 691 (Div. 1) ›

CF 1458F - Range Diameter Sum

The failure here is not algorithmic at all. The GCD reduction logic for this problem is correct and already known to be optimal. The actual bug is purely in the execution wrapper and not in the solution idea.

Practice › Codeforces Solutions › Codeforces Round 691 (Div. 1) ›

CF 1458E - Nim Shortcuts

We are asked to analyze a variation of the two-heap Nim game. In classic Nim with two heaps, each player can take any positive number of stones from either heap. The player who cannot make a move loses.

Practice › Codeforces Solutions › Codeforces Round 691 (Div. 1) ›

CF 1458C - Latin Square

We start with an (n times n) Latin square. Every row is a permutation of (1 ldots n), and every column is also a permutation of (1 ldots n). A sequence of operations modifies the matrix. Four operations perform cyclic shifts of rows or columns.

Practice › Codeforces Solutions › Codeforces Round 691 (Div. 1) ›

CF 1458A - Row GCD

The problem presents us with two sequences of integers: the first sequence a contains n elements, and the second sequence b contains m elements.

Practice › Codeforces Solutions › Codeforces Round 691 (Div. 1) ›

CF 1458D - Flip and Reverse

We are given a binary string consisting of 0's and 1's, and we are allowed to perform a specific operation any number of times.

Practice › Codeforces Solutions › Codeforces Round 691 (Div. 1) ›

CF 1458B - Glass Half Spilled

We have up to 100 glasses. Glass i can hold ai units of water and currently contains bi units. We are allowed to move water between glasses. The catch is that every transfer loses half of the transferred amount.