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advent-of-code/2016/rust/src/day_02.rs

116 lines
2.3 KiB

use std::char;
pub fn solve(input: &str) -> String {
let arrangement = vec![
vec![None, None, Some('1'), None, None],
vec![None, Some('2'), Some('3'), Some('4'), None],
vec![Some('5'), Some('6'), Some('7'), Some('8'), Some('9')],
vec![None, Some('A'), Some('B'), Some('C'), None],
vec![None, None, Some('D'), None, None],
];
let mut keypad = Keypad {
arrangement: arrangement,
current: (0, 2),
};
let mut answer = String::new();
for c in input.chars() {
match c {
'U' => {
keypad.move_(Dir::Up);
}
'D' => {
keypad.move_(Dir::Down);
}
'L' => {
keypad.move_(Dir::Left);
}
'R' => {
keypad.move_(Dir::Right);
}
'\n' => {
answer.push(keypad.button());
}
_ => {
unreachable!();
}
}
}
answer.push(keypad.button());
answer
}
#[test]
fn test_solve() {
let instructions = "ULL
RRDDD
LURDL
UUUUD";
assert_eq!(solve(instructions), "5DB3".to_string());
}
struct Keypad {
arrangement: Vec<Vec<Option<char>>>,
current: (usize, usize),
}
impl Keypad {
fn move_(&mut self, dir: Dir) {
let (dx, dy): (isize, isize) = match dir {
Dir::Up => (0, -1),
Dir::Down => (0, 1),
Dir::Left => (-1, 0),
Dir::Right => (1, 0),
};
let x = (self.current.0 as isize + dx) as usize;
let y = (self.current.1 as isize + dy) as usize;
if self.button_at(x, y).is_some() {
self.current = (x, y);
}
}
fn button(&self) -> char {
let (x, y) = self.current;
8 years ago
self.arrangement[y][x].unwrap()
}
fn button_at(&self, x: usize, y: usize) -> Option<char> {
self.arrangement.get(y).and_then(|row| row.get(x).and_then(|c| *c))
}
}
enum Dir {
Up,
Down,
Left,
Right,
}
#[test]
fn test_keypad() {
let arrangement = vec![
vec!['1', '2', '3'],
vec!['4', '5', '6'],
vec!['7', '8', '9'],
]
.iter()
.map(|row| row.iter().map(|x| Some(*x)).collect())
.collect();
let mut keypad = Keypad {
arrangement: arrangement,
current: (1, 1),
};
assert_eq!(keypad.button_at(1, 1), Some('5'));
assert_eq!(keypad.button(), '5');
keypad.move_(Dir::Up);
assert_eq!(keypad.button(), '2');
keypad.move_(Dir::Up);
assert_eq!(keypad.button(), '2');
}