year2017/
day01.rs

1use utils::prelude::*;
2
3/// Adding matching digits.
4#[derive(Clone, Debug)]
5pub struct Day01<'a> {
6    input: &'a [u8],
7}
8
9impl<'a> Day01<'a> {
10    pub fn new(input: &'a str, _: InputType) -> Result<Self, InputError> {
11        if let Some(b) = input.bytes().find(|b| !b.is_ascii_digit()) {
12            Err(InputError::new(input, b as char, "expected digit"))
13        } else {
14            Ok(Self {
15                input: input.as_bytes(),
16            })
17        }
18    }
19
20    #[must_use]
21    pub fn part1(&self) -> u32 {
22        self.input
23            .iter()
24            .zip(self.input.iter().cycle().skip(1))
25            .map(|(&a, &b)| if a == b { (a - b'0') as u32 } else { 0 })
26            .sum()
27    }
28
29    #[must_use]
30    pub fn part2(&self) -> u32 {
31        self.input
32            .iter()
33            .zip(self.input.iter().cycle().skip(self.input.len() / 2))
34            .map(|(&a, &b)| if a == b { (a - b'0') as u32 } else { 0 })
35            .sum()
36    }
37}
38
39examples!(Day01<'_> -> (u32, u32) [
40    {input: "1122", part1: 3},
41    {input: "1111", part1: 4},
42    {input: "1234", part1: 0},
43    {input: "91212129", part1: 9},
44    {input: "1212", part2: 6},
45    {input: "1221", part2: 0},
46    {input: "123425", part2: 4},
47    {input: "123123", part2: 12},
48    {input: "12131415", part2: 4},
49]);
year2017/day01.rs

year2017/
day01.rs
