Codeforces Round 784 (Div. 4)

Solutions for Codeforces Round 784 (Div. 4) (contest 1669). 7/8 problems verified against sample I/O. Difficulty range: 800-1300.

8 items

Codeforces Round 784 (Div. 4)

Type: Div. 4 | Problems: 8 | Verified: 7/8 | Rating range: 800-1300 | Time: 18m 23s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Division?	800	implementation	1m 33s	✓
B	Triple	800	implementation, sortings	7m 27s	✓
C	Odd/Even Increments	800	greedy, implementation, math	1m 37s	✓
D	Colorful Stamp	1100	implementation	1m 37s	✓
E	2-Letter Strings	1200	data-structures, math, strings	1m 33s	✓
F	Eating Candies	1100	binary-search, data-structures, greedy	1m 23s	✓
G	Fall Down	1200	dfs-and-similar, implementation	1m 54s	✗
H	Maximal AND	1300	bitmasks, greedy, math	1m 19s	✓

Practice › Codeforces Solutions › Codeforces Round 784 (Div. 4) ›

CF 1669B - Triple

The problem asks us to find any number in an array that occurs at least three times. We are given multiple test cases, and for each test case, an array of integers is provided. The integers are guaranteed to be between 1 and the size of the array.

Practice › Codeforces Solutions › Codeforces Round 784 (Div. 4) ›

CF 1669H - Maximal AND

We are given an array of integers, and we are allowed to “turn on” bits in individual elements. Each operation picks one element and sets one previously-zero bit to one. We may do this at most k times across the entire array.

Practice › Codeforces Solutions › Codeforces Round 784 (Div. 4) ›

CF 1669G - Fall Down

We are given a rectangular grid of size $n times m$ consisting of empty cells, stones, and obstacles. Stones are represented by '', empty cells by '.', and obstacles by 'o'.

Practice › Codeforces Solutions › Codeforces Round 784 (Div. 4) ›

CF 1669F - Eating Candies

We are given a sequence of candy weights laid out in a straight line. Two people, Alice and Bob, consume candies under a strict constraint: Alice can only take a prefix from the left end, while Bob can only take a suffix from the right end.

Practice › Codeforces Solutions › Codeforces Round 784 (Div. 4) ›

CF 1669E - 2-Letter Strings

We are given a collection of short strings, each consisting of exactly two lowercase letters from a small alphabet.

Practice › Codeforces Solutions › Codeforces Round 784 (Div. 4) ›

CF 1669D - Colorful Stamp

We are given a line of cells that starts completely empty, and we are allowed to apply a special operation that always acts on exactly two adjacent positions. Each application recolors those two cells into different colors, one red and one blue, in either order.

Practice › Codeforces Solutions › Codeforces Round 784 (Div. 4) ›

CF 1669C - Odd/Even Increments

We are given an array of integers where we are allowed to repeatedly apply two global operations. One operation increments every element at odd positions, and the other increments every element at even positions.

Practice › Codeforces Solutions › Codeforces Round 784 (Div. 4) ›

CF 1669A - Division?

Each test case gives a single integer representing a Codeforces user rating, and the task is to classify that rating into one of four fixed intervals, each corresponding to a division number. The mapping is purely threshold-based.