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advent-of-code/2015/rust/src/day_03.rs

140 lines
3.1 KiB

9 years ago
use std::collections::HashMap;
use std::fmt;
use std::ops::Add;
use std::str::Chars;
pub fn solve(input: &str) -> i32 {
let mut santa = String::new();
let mut robo_santa = String::new();
let mut iter = input.chars();
loop {
match iter.next() {
Some(c) => santa.push(c),
None => break,
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}
match iter.next() {
Some(c) => robo_santa.push(c),
None => break,
}
}
let mut houses: HashMap<Point, u32> = HashMap::new();
Santa::houses_visited(&santa, &mut houses);
Santa::houses_visited(&robo_santa, &mut houses);
houses.len() as i32
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}
struct Santa<'a> {
location: Point,
directions: Chars<'a>,
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}
impl<'a> Santa<'a> {
fn new(directions: &str) -> Santa {
Santa {
location: Point::origin(),
directions: directions.chars(),
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}
}
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fn houses_visited(directions: &str, houses: &mut HashMap<Point, u32>) {
let santa = Santa::new(directions);
houses.insert(santa.location, 1);
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for point in santa {
*houses.entry(point).or_insert(0) += 1;
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}
}
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}
impl<'a> Iterator for Santa<'a> {
type Item = Point;
fn next(&mut self) -> Option<Point> {
let offset = match self.directions.next() {
Some('^') => Point { x: 0, y: 1 },
Some('v') => Point { x: 0, y: -1 },
Some('>') => Point { x: 1, y: 0 },
Some('<') => Point { x: -1, y: 0 },
_ => return None,
};
self.location = self.location + offset;
Some(self.location)
}
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}
#[test]
fn test_one() {
let directions = ">";
let santa = Santa::new(directions);
let points = santa.collect::<Vec<Point>>();
let expected = vec![Point { x: 1, y: 0 }];
assert_eq!(expected, points);
let mut houses: HashMap<Point, u32> = HashMap::new();
Santa::houses_visited(directions, &mut houses);
assert_eq!(2, houses.len());
assert_eq!(&1, houses.get(&Point::origin()).unwrap());
assert_eq!(&1, houses.get(&Point { x: 1, y: 0 }).unwrap());
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}
#[test]
fn test_two() {
let directions = "^>v<";
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let mut houses: HashMap<Point, u32> = HashMap::new();
Santa::houses_visited(directions, &mut houses);
assert_eq!(4, houses.len());
assert_eq!(&2, houses.get(&Point::origin()).unwrap());
assert_eq!(&1, houses.get(&Point { x: 1, y: 0 }).unwrap());
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}
#[test]
fn test_three() {
let directions = "^v^v^v^v^v";
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let mut houses: HashMap<Point, u32> = HashMap::new();
Santa::houses_visited(directions, &mut houses);
assert_eq!(2, houses.len());
assert_eq!(&6, houses.get(&Point::origin()).unwrap());
assert_eq!(&5, houses.get(&Point { x: 0, y: 1 }).unwrap());
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}
#[derive(Clone,Copy,Debug,Eq,Hash,PartialEq)]
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struct Point {
x: i32,
y: i32,
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}
impl Point {
fn origin() -> Point {
Point { x: 0, y: 0 }
}
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}
impl Add for Point {
type Output = Point;
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fn add(self, other: Point) -> Point {
Point {
x: self.x + other.x,
y: self.y + other.y,
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}
}
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}
impl fmt::Display for Point {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "({}, {})", self.x, self.y)
}
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}
#[test]
fn test_point() {
let point = Point { x: 10, y: -10 };
let offset = Point { x: -10, y: 10 };
assert_eq!(Point::origin(), point + offset);
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}