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use std::fmt::{Display as FmtDisplay, Error as FmtError, Formatter};
use std::io::{self, Read};
use std::ops::{Index, IndexMut};
use std::str::FromStr;
enum Operation {
Rect(usize, usize),
RotateRow(usize, usize),
RotateColumn(usize, usize),
}
impl FromStr for Operation {
type Err = ();
fn from_str(s: &str) -> Result<Self, ()> {
if s.starts_with("rect") {
let mut iter = s[5..].split('x');
let width = iter.next().ok_or(())?.parse().map_err(|_| ())?;
let height = iter.next().ok_or(())?.parse().map_err(|_| ())?;
Ok(Operation::Rect(width, height))
} else if s.starts_with("rotate row") {
let mut iter = s[13..].split(" by ");
let y = iter.next().ok_or(())?.parse().map_err(|_| ())?;
let count = iter.next().ok_or(())?.parse().map_err(|_| ())?;
Ok(Operation::RotateRow(y, count))
} else if s.starts_with("rotate column") {
let mut iter = s[16..].split(" by ");
let x = iter.next().ok_or(())?.parse().map_err(|_| ())?;
let count = iter.next().ok_or(())?.parse().map_err(|_| ())?;
Ok(Operation::RotateColumn(x, count))
} else {
Err(())
}
}
}
struct Display {
width: usize,
height: usize,
pixels: Box<[bool]>,
}
impl Index<(usize, usize)> for Display {
type Output = bool;
fn index(&self, index: (usize, usize)) -> &bool {
&self.pixels[index.1 * self.width + index.0]
}
}
impl IndexMut<(usize, usize)> for Display {
fn index_mut(&mut self, index: (usize, usize)) -> &mut bool {
&mut self.pixels[index.1 * self.width + index.0]
}
}
impl Display {
fn new(width: usize, height: usize) -> Self {
Display {
width: width,
height: height,
pixels: vec![false; width * height].into_boxed_slice(),
}
}
fn apply(&mut self, operation: Operation) {
match operation {
Operation::Rect(width, height) => {
for y in 0..height {
for x in 0..width {
self[(x, y)] = true;
}
}
},
Operation::RotateRow(y, count) => {
for _ in 0..count {
let last = self[(self.width - 1, y)];
for x in (1..self.width).rev() {
self[(x, y)] = self[(x - 1, y)];
}
self[(0, y)] = last;
}
},
Operation::RotateColumn(x, count) => {
for _ in 0..count {
let last = self[(x, self.height - 1)];
for y in (1..self.height).rev() {
self[(x, y)] = self[(x, y - 1)];
}
self[(x, 0)] = last;
}
},
}
}
fn pixels_lit(&self) -> usize {
self.pixels.iter().filter(|&&p| p).count()
}
}
impl FmtDisplay for Display {
fn fmt(&self, f: &mut Formatter) -> Result<(), FmtError> {
for y in 0..self.height {
for x in 0..self.width {
if self[(x, y)] {
write!(f, "#")?;
} else {
write!(f, " ")?;
}
}
write!(f, "\n")?;
}
Ok(())
}
}
fn solve(width: usize, height: usize, input: &str) -> Display {
let mut display = Display::new(width, height);
for line in input.lines() {
display.apply(line.parse().unwrap());
}
display
}
fn main() {
let mut input = String::new();
io::stdin().read_to_string(&mut input).unwrap();
let display = solve(50, 6, &input);
println!("Part 1: {}", display.pixels_lit());
println!("Part 2:\n{}", display);
}
#[test]
fn part1() {
let input = "
rect 3x2
rotate column x=1 by 1
rotate row y=0 by 4
rotate row x=1 by 1
";
assert_eq!(6, solve(7, 3, input.trim()).pixels_lit());
}
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