Hypyt

use std::io::{
    BufReader,
    BufWriter,
    BufRead,
    Write,
    stdin,
    stdout,
    Stdin,
    StdoutLock
};
use std::collections::{
    HashMap,
    HashSet,
    VecDeque
};

fn main() {
    let mut reader: BufReader<Stdin> = BufReader::new(stdin());
    let mut writer: BufWriter<StdoutLock<'_>> = BufWriter::new(stdout().lock());

    let mut input: String = String::new();
    reader.read_line(&mut input).unwrap();
    let input: Vec<usize> = input.trim().split(" ").map(|s: &str| s.parse::<usize>().unwrap()).collect();
 
    let total_nodes: usize = input[0] * input[1] + input[0] + input[1];
    let mut graph: Vec<Vec<usize>> = vec![vec![]; total_nodes];
    parse_graph(&input, &mut reader, &mut graph);
 
    let mut queries: HashSet<usize> = HashSet::new();
    let mut queries_order: Vec<(usize, usize)> = Vec::new();
    for _ in 0..input[2] {
        let mut query: String = String::new();
        reader.read_line(&mut query).unwrap();
        let query: Vec<usize> = query.trim().split(" ").map(|s: &str| s.parse::<usize>().unwrap()).collect();
 
        let start: usize = (query[0] - 1) * input[1] + (query[1] - 1);
        let goal: usize = (query[2] - 1) * input[1] + (query[3] - 1);
        if !queries.contains(&start) { queries.insert(start); }
        queries_order.push((start, goal));
    }
 
    let mut distance_table: HashMap<usize, HashMap<usize, usize>> = HashMap::new();
    get_distance_table(&mut distance_table, &graph, &queries, total_nodes);
 
    for (start, goal) in queries_order {
        match distance_table.get(&start).and_then(|g: &HashMap<usize, usize>| g.get(&goal)) {
            Some(dist) => { writeln!(writer, "{}", dist / 2).unwrap(); }
            None => { writeln!(writer, "-1").unwrap(); }
        }
    }
}
 
fn parse_graph(input: &Vec<usize>, reader: &mut BufReader<Stdin>, graph: &mut Vec<Vec<usize>>) {
    for r in 0..input[0] {
        let mut row: String = String::new();
        reader.read_line(&mut row).unwrap();
        
        for (c, cell) in row.chars().enumerate() {
            if cell == '.' {
                let cell_index: usize = r * input[1] + c;
                let row_index: usize = input[0] * input[1] + r;
                let col_index: usize = input[0] * input[1] + input[0] + c;

                graph[cell_index].extend([row_index, col_index]);
                graph[row_index].push(cell_index);
                graph[col_index].push(cell_index);
            }
        }
    }
}
 
fn get_distance_table(table: &mut HashMap<usize, HashMap<usize, usize>>, graph: &Vec<Vec<usize>>, queries: &HashSet<usize>, total_nodes: usize) {
    for &root in queries {
        table.insert(root, HashMap::new());
        bfs(root, table.get_mut(&root).unwrap(), graph, total_nodes);
    }
}
 
fn bfs(start: usize, dist: &mut HashMap<usize, usize>, graph: &Vec<Vec<usize>>, total_nodes: usize) {
    dist.insert(start, 0);
    let mut queue: VecDeque<usize> = VecDeque::from([start]);
    let mut visited: Vec<bool> = vec![false; total_nodes];
    visited[start] = true;
 
    while let Some(current) = queue.pop_front() {
        let current_dist: usize = *dist.get(&current).unwrap();
        for &neighbour in graph[current].iter() {
            if !visited[neighbour] {
                dist.insert(neighbour, current_dist + 1);
                queue.push_back(neighbour);
                visited[neighbour] = true;
            }
        }
    }
}

Test 1 (public)

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

Test 5

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

Test 6

Group: 2, 5

Verdict: TIME LIMIT EXCEEDED

Test 7

Group: 2, 5

Verdict: TIME LIMIT EXCEEDED

Test 8

Group: 2, 5

Verdict: ACCEPTED

Test 9

Group: 3, 4, 5

Verdict: ACCEPTED

Test 10

Group: 3, 4, 5

Verdict: ACCEPTED

Test 11

Group: 3, 4, 5

Verdict: ACCEPTED

Test 12

Group: 4, 5

Verdict: TIME LIMIT EXCEEDED

Test 13

Group: 4, 5

Verdict: TIME LIMIT EXCEEDED

Test 14

Group: 4, 5

Verdict: ACCEPTED

Test 15

Group: 5

Verdict: TIME LIMIT EXCEEDED

Test 16

Group: 5

Verdict: TIME LIMIT EXCEEDED

Test 17

Group: 5

Verdict: TIME LIMIT EXCEEDED

Test 18

Group: 5

Verdict: TIME LIMIT EXCEEDED

Test 19

Group: 5

Verdict: ACCEPTED

Test 20

Group: 5

Verdict: ACCEPTED

Test 21

Group: 5

Verdict: ACCEPTED

Test 22

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

Test 23

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

Test 24

Group: 5

Verdict: ACCEPTED

Test 25

Group: 5

Verdict: ACCEPTED

Test 26

Group: 5

Verdict: TIME LIMIT EXCEEDED

Test 27

Group: 5

Verdict: ACCEPTED