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use anyhow::Context;
use crate::{Problem, Solution};
pub struct Day01;
impl Problem for Day01 {
const DAY: u8 = 1;
const INPUT: &'static str = include_str!("../input/day_01.txt");
}
impl Solution for Day01 {
type Answer1 = usize;
type Answer2 = usize;
fn part_1(input: &str) -> anyhow::Result<Self::Answer1> {
input.trim().split('\n').try_fold(0, |acc, line| {
let first = line
.chars()
.find_map(|c| c.to_digit(10).map(|n| n as usize))
.context("Failed to find first number")?;
let last = line
.chars()
.rev()
.find_map(|c| c.to_digit(10).map(|n| n as usize))
.unwrap_or(first);
Ok(acc + first * 10 + last)
})
}
fn part_2(input: &str) -> anyhow::Result<Self::Answer2> {
let words = [
"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine",
];
input.trim().split('\n').try_fold(0, |acc, line| {
let mut buf = String::new();
let first = line
.chars()
.find_map(|c| {
buf.push(c);
words
.iter()
.enumerate()
.find_map(|(n, w)| buf.contains(w).then_some(n))
.or_else(|| c.to_digit(10).map(|n| n as usize))
})
.context("Failed to find first number")?;
buf.clear();
let last = line
.chars()
.rev()
.find_map(|c| {
buf.insert(0, c);
words
.iter()
.enumerate()
.find_map(|(n, w)| buf.contains(w).then_some(n))
.or_else(|| c.to_digit(10).map(|n| n as usize))
})
.unwrap_or(first);
Ok(acc + first * 10 + last)
})
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_part_1() -> anyhow::Result<()> {
let input = indoc::indoc! {"
1abc2
pqr3stu8vwx
a1b2c3d4e5f
treb7uchet
"};
Ok(assert_eq!(142, Day01::part_1(input)?))
}
#[test]
fn test_part_2() -> anyhow::Result<()> {
let input = indoc::indoc! {"
two1nine
eightwothree
abcone2threexyz
xtwone3four
4nineeightseven2
zoneight234
7pqrstsixteen
"};
Ok(assert_eq!(281, Day01::part_2(input)?))
}
}
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