Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2)

Solutions for Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2) (contest 1864). 1/9 problems verified against sample I/O. Difficulty range: 800-3500.

9 items

Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2)

Type: Div. 1+2 | Problems: 9 | Verified: 1/9 | Rating range: 800-3500 | Time: 17m 20s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Increasing and Decreasing	800	constructive-algorithms, greedy, implementation	1m 40s	✗
B	Swap and Reverse	1100	constructive-algorithms, greedy, sortings	1m 10s	✓
C	Divisor Chain	1300	bitmasks, constructive-algorithms, math	3m 22s	✗
D	Matrix Cascade	1700	brute-force, constructive-algorithms, data-structures	1m 36s	✗
E	Guess Game	2100	bitmasks, data-structures, games	2m 9s	✗
F	Exotic Queries	2300	data-structures, implementation, sortings	1m 51s	✗
G	Magic Square	3100	combinatorics, constructive-algorithms, implementation	1m 39s	✗
H	Asterism Stream	3200	dp, math, matrices	1m 26s	✗
I	Future Dominators	3500	graphs, greedy	2m 27s	✗

Practice › Codeforces Solutions › Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2) ›

CF 1864I - Future Dominators

Let the grid cells be vertices of an $n times n$ grid graph. A final placement of the numbers $1 ldots n^2$ is valid if every vertex except the one containing $1$ has at least one adjacent vertex with a smaller number.

Practice › Codeforces Solutions › Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2) ›

CF 1864G - Magic Square

We start with two square boards of size $n times n$, each containing the numbers $1$ to $n^2$ exactly once. Think of each number as a labeled tile. The initial board is some arrangement of these tiles, and we want to transform it into a target arrangement.

Practice › Codeforces Solutions › Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2) ›

CF 1864H - Asterism Stream

We are asked to compute the expected number of moves to reach or exceed a target integer n starting from x = 1 when in each move you either increment x by 1 or double it, each with probability 1/2.

Practice › Codeforces Solutions › Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2) ›

CF 1864F - Exotic Queries

We are given an array of integers a of length n. For each query (l, r), we need to zero out every number in a that lies within the range [l, r] using a set of subtraction operations.

Practice › Codeforces Solutions › Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2) ›

CF 1864E - Guess Game

We are given a multiset of integers, and we repeatedly imagine picking two positions independently, forming an ordered pair of values $(a, b)$. Along with $a$ and $b$, both players also learn the bitwise OR $x = a mid b$.

Practice › Codeforces Solutions › Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2) ›

CF 1864C - Divisor Chain

The failure here is not algorithmic at all. The expected logic is correct: the answer is the minimum absolute value in the array. The issue is purely an implementation bug that leads to no output being printed.

Practice › Codeforces Solutions › Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2) ›

CF 1864D - Matrix Cascade

We are given a square grid filled with bits, and the goal is to turn every cell into zero. The only allowed move flips values in a very specific geometric pattern: you pick a cell as a “center”, and it toggles itself and all cells strictly below it that lie within a…

Practice › Codeforces Solutions › Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2) ›

CF 1864A - Increasing and Decreasing

The problem gives us three integers: a starting value x, an ending value y, and a length n. We need to build an array a of length n that starts at x and ends at y, is strictly increasing, and has strictly decreasing consecutive differences.

Practice › Codeforces Solutions › Harbour.Space Scholarship Contest 2023-2024 (Div. 1 + Div. 2) ›

CF 1864B - Swap and Reverse

We are given a string and two kinds of moves that let us rearrange its characters in a constrained way. One move swaps characters that are two positions apart, and the other reverses a contiguous block of fixed length $k$.