Codeforces Round 913 (Div. 3)

Solutions for Codeforces Round 913 (Div. 3) (contest 1907). 2/7 problems verified against sample I/O. Difficulty range: 800-2200.

7 items

Codeforces Round 913 (Div. 3)

Type: Div. 3 | Problems: 7 | Verified: 2/7 | Rating range: 800-2200 | Time: 14m 6s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Rook	800	implementation	1m 56s	✗
B	YetnotherrokenKeoard	1000	data-structures, implementation, strings	2m 36s	✓
C	Removal of Unattractive Pairs	1200	constructive-algorithms, greedy, math	2m 17s	✗
D	Jumping Through Segments	1400	binary-search, constructive-algorithms	1m 40s	✗
E	Good Triples	1600	brute-force, combinatorics, number-theory	1m 55s	✓
F	Shift and Reverse	1800	greedy, sortings	1m 56s	✗
G	Lights	2200	brute-force, constructive-algorithms, dfs-and-similar	1m 46s	✗

Practice › Codeforces Solutions › Codeforces Round 913 (Div. 3) ›

CF 1907G - Lights

Each test case describes a system of lights where every switch affects exactly two lights. If we press switch i, it toggles light i and also toggles another fixed light a[i]. Toggling means flipping between on and off.

Practice › Codeforces Solutions › Codeforces Round 913 (Div. 3) ›

CF 1907F - Shift and Reverse

We are given an array and allowed to modify it using only two rigid global operations. One operation rotates the array by one position to the right, moving the last element to the front. The other operation reverses the entire array.

Practice › Codeforces Solutions › Codeforces Round 913 (Div. 3) ›

CF 1907E - Good Triples

We need to count ordered triples of non-negative integers $(a,b,c)$ whose sum is exactly $n$. The unusual part is the digit-sum condition: $$text{digsum}(a)+text{digsum}(b)+text{digsum}(c)=text{digsum}(n).$$ A triple is counted only if both conditions hold.

Practice › Codeforces Solutions › Codeforces Round 913 (Div. 3) ›

CF 1907D - Jumping Through Segments

We are given a sequence of intervals on the number line, and we simulate a constrained movement process across them. The player starts at position 0. For each interval in order, the player makes one move, and after that move they must land inside the corresponding interval.

Practice › Codeforces Solutions › Codeforces Round 913 (Div. 3) ›

CF 1907B - YetnotherrokenKeoard

We are asked to simulate a keyboard with broken keys that behave like selective backspaces. Every lowercase 'b' deletes the most recent lowercase letter in the typed string, and every uppercase 'B' deletes the most recent uppercase letter. All other letters are appended normally.

Practice › Codeforces Solutions › Codeforces Round 913 (Div. 3) ›

CF 1907C - Removal of Unattractive Pairs

We are given a string of lowercase letters, and we can repeatedly remove pairs of adjacent letters if they are different. The goal is to reduce the string to its minimum possible length.

Practice › Codeforces Solutions › Codeforces Round 913 (Div. 3) ›

CF 1907A - Rook

The task is to list all legal moves of a rook from a given square on an empty chessboard. A rook moves horizontally along its row or vertically along its column, stopping only at the edges of the board.