Advent of Code 2016 Day 8

extern crate regex;
use regex::Regex;
use std::collections::{HashMap, HashSet};
use std::io;


fn read_line() -> String {
    let mut input = String::new();
    io::stdin().read_line(&mut input).unwrap();
    input.trim_right().to_owned()
}

fn parse_i32<'a, T: Into<&'a str>>(s: T) -> i32 {
    s.into().parse().unwrap()
}

fn parse_usize<'a, T: Into<&'a str>>(s: T) -> usize {
    s.into().parse().unwrap()
}

fn main() {
    let mut sum = 0;
    let rxrect = Regex::new(r"^rect (\d*)x(\d*)$").unwrap();
    let rxrow = Regex::new(r"^rotate row y=(\d*) by (\d*)$").unwrap();
    let rxcol = Regex::new(r"^rotate column x=(\d*) by (\d*)$").unwrap();

    const W: usize = 50;
    const H: usize = 6;
    let mut disp = vec![vec![false;W];H];

    loop {
        let s = read_line();
        if s.is_empty() { break };

        if rxrect.is_match(&s) {
            let caps = rxrect.captures(&s).unwrap();
            let cx = parse_usize(caps.at(1).unwrap());
            let cy = parse_usize(caps.at(2).unwrap());
            println!("{} {}", cx, cy);
            for x in 0..cx {
                for y in 0..cy {
                    disp[y][x] = true;
                }
            }
        } else if rxrow.is_match(&s) {
            let caps = rxrow.captures(&s).unwrap();
            let cy = parse_usize(caps.at(1).unwrap());
            let cnt = parse_usize(caps.at(2).unwrap());
            println!("{} {}", cy, cnt);
            let v = disp[cy].clone();
            for i in 0..W {
                disp[cy][(i+cnt)%W] = v[i];
            }

        } else if rxcol.is_match(&s) {
            let caps = rxcol.captures(&s).unwrap();
            let cx = parse_usize(caps.at(1).unwrap());
            let cnt = parse_usize(caps.at(2).unwrap());
            println!("{} {}", cx, cnt);
            let mut v = vec![];
            for i in 0..H {
                v.push(disp[i][cx]);
            }
            for i in 0..H {
                disp[(i+cnt)%H][cx] = v[i];
            }
        } else {
            panic!("Wrong input");
        }
        for y in 0..H {
            for x in 0..W {
                print!("{}", if disp[y][x] {'X'} else {'.'});
            }
            println!("");
        }
        println!("");

    }
    for y in 0..disp.len() {
        for x in 0..disp[0].len() {
            if disp[y][x] {
                sum += 1;
            }
        }
    }
    println!("{:?}", sum);
}