Ratsun reitit

use std::io::{self, BufRead};

fn main() {
    let mut lines = io::BufReader::new(io::stdin()).lines();

    let n: i32 = lines.next().unwrap().unwrap().parse().unwrap();

    let mut board = vec![vec![None; n as usize]; n as usize];

    board[0][0] = Some(0);
    let mut just_visited = vec![(0, 0)];

    while !just_visited.is_empty() {
        let mut new_just_visited = Vec::new();

        for (x, y) in just_visited {
            for &(dx, dy) in &[
                (1, 2),
                (1, -2),
                (-1, 2),
                (-1, -2),
                (2, 1),
                (2, -1),
                (-2, 1),
                (-2, -1),
            ] {
                if 0 <= x + dx
                    && x + dx < n
                    && 0 <= y + dy
                    && y + dy < n
                    && board[(x + dx) as usize][(y + dy) as usize].is_none()
                {
                    if !new_just_visited.contains(&(x + dx, y + dy)) {
                        new_just_visited.push((x + dx, y + dy));
                    }
                    board[(x + dx) as usize][(y + dy) as usize] =
                        Some(board[x as usize][y as usize].unwrap() + 1);
                }
            }
        }

        just_visited = new_just_visited;
    }

    for x in 0..n {
        for y in 0..n {
            print!("{} ", board[x as usize][y as usize].unwrap());
        }
        println!();
    }
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: ACCEPTED

Test 5

Group: 1, 2, 3

Verdict: ACCEPTED

Test 6

Group: 1, 2, 3

Verdict: ACCEPTED

Test 7

Group: 1, 2, 3

Verdict: ACCEPTED

Test 8

Group: 2, 3

Verdict: ACCEPTED

Test 9

Group: 2, 3

Verdict: ACCEPTED

Test 10

Group: 2, 3

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED