86 lines
2.0 KiB
Rust
86 lines
2.0 KiB
Rust
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use std::fs::File;
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use std::io::{BufRead, BufReader, Lines};
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// BOILERPLATE
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type InputIter = Lines<BufReader<File>>;
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fn get_input() -> InputIter {
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let f = File::open("input").unwrap();
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let br = BufReader::new(f);
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br.lines()
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}
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fn main() {
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println!("Problem 1 solution: {}", problem1(get_input()));
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println!("Problem 2 solution: {}", problem2(get_input()));
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}
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// PROBLEM1 solution
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fn problem1_lineval(line: &String) -> u64 {
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// forward iterate to find the first numeric value
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let first = line.chars().find(|c| c.is_digit(10)).unwrap();
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let last = line.chars().rev().find(|c| c.is_digit(10)).unwrap();
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(first.to_digit(10).unwrap() * 10 + last.to_digit(10).unwrap()).into()
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}
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fn problem1(input: InputIter) -> u64 {
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input.map(|line| problem1_lineval(&line.unwrap())).sum()
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}
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// PROBLEM2 solution
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const DIGITS: &[(&str, u64)] = &[
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("one", 1),
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("two", 2),
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("three", 3),
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("four", 4),
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("five", 5),
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("six", 6),
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("seven", 7),
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("eight", 8),
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("nine", 9),
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];
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fn problem2_numeric(start: &str) -> Option<u64> {
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let char = start.chars().nth(0).unwrap();
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if char.is_numeric() {
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Some(char.to_digit(10).unwrap().into())
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} else {
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for (s, n) in DIGITS {
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if start.starts_with(s) {
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return Some(*n);
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}
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}
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None
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}
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}
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fn problem2_lineval(line: &String) -> u64 {
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let mut first = None;
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for pos in 0..line.len() {
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let (_, sub) = line.split_at(pos);
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if let Some(n) = problem2_numeric(sub) {
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first = Some(n);
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break;
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} else {
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continue;
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}
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}
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let mut second = None;
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for pos in (0..line.len()).rev() {
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let (_, sub) = line.split_at(pos);
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if let Some(n) = problem2_numeric(sub) {
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second = Some(n);
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break;
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} else {
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continue;
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}
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}
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first.unwrap() * 10 + second.unwrap()
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}
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fn problem2(input: InputIter) -> u64 {
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input.map(|line| problem2_lineval(&line.unwrap())).sum()
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}
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