main.rs

use std::io::prelude::*;
use std::io::BufReader;
use std::str::FromStr;
use std::fs::File;
#[derive(Copy, Clone, Debug)]
struct Position {
    x: usize,
    y: usize
}

impl Position {
    fn new(x: usize, y: usize) -> Position {
        Position { x: x, y: y }
    }
    fn new_inverse(y: usize, x: usize) -> Position {
        Position { x: x, y: y }
    }
    fn into(&self) -> (usize, usize) {
        (self.x, self.y)
    }
}

fn square(pos: Position, rocks: &[Position], size: usize) -> usize {
    let mut area = 0;
    'a: loop {
        area+=1;
        for rock in rocks {
            for y in pos.y..area+1 {
                for x in pos.x..area+1 {
                    if (rock.x as isize - x as isize).abs() == 1 || (rock.y as isize - y as isize).abs() == 1 {
                        break 'a;
                    }
                }
            }
        }
    }

    area
}
            


fn main() { 
    let mut file = BufReader::new(File::open("/tmp/field.txt").unwrap());
    let mut size_str = String::new();
    let mut squares: Vec<(Position, Position)> = Vec::new();
    file.read_line(&mut size_str);
    let size = usize::from_str(&size_str.trim_right()).unwrap();
    let mut rocks = Vec::new();
    for (y, line) in (&mut file).lines().take(size).enumerate() {
        let line = line.unwrap();
        for (idx, x) in line.chars().enumerate() {
            if x == 'X' {
                rocks.push(Position::new(idx, y));
            }
        }
    }
    file.seek(std::io::SeekFrom::Start(0));
    let mut buf = String::new();
    file.read_to_string(&mut buf);
    println!("{}", buf);
    let mut area = 0;
    for y in 0..size {
        'a: for x in 0..size {
            for square in &squares {
                if (x >= square.0.x && x <= square.1.x) && (y >= square.0.y && y >= square.1.y) {
                    continue 'a;
                }
            }       
            let area2 = square(Position::new(x, y), &rocks, size);
            if area2 > area { area = area2; }
            squares.push((Position::new(x, y), Position::new(x+area2, y+area2)));
        }
    }
    println!("{} dropships", area);
    //println!("{:?}", rocks);
}