62 lines
1.7 KiB
Rust
62 lines
1.7 KiB
Rust
use std::fs::read_to_string;
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pub fn day_main() {
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let input = read_to_string("input/day03.txt").unwrap();
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let input = input.trim();
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println!(" part1: {}", part1(input));
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println!(" part2: {}", part2(input));
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}
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type RiddleResult = i64;
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fn part1(input: &str) -> RiddleResult {
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let r = regex::Regex::new(r"mul\((\d{1,3}),(\d{1,3})\)").unwrap();
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r.captures_iter(input)
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.map(|c| {
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let a: i64 = c[1].parse().unwrap();
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let b: i64 = c[2].parse().unwrap();
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a * b
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})
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.sum()
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}
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fn part2(input: &str) -> RiddleResult {
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let r = regex::Regex::new(r"do\(\)|don't\(\)|mul\((\d{1,3}),(\d{1,3})\)").unwrap();
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r.captures_iter(input)
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// (enabled, result): initially enabled; sum up the result over all enabled multiplications
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.fold((true, 0), |(enabled, result), c| {
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let s = c.get(0).unwrap().as_str();
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match s {
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"do()" => (true, result),
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"don't()" => (false, result),
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_ => {
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let a: i64 = c[1].parse().unwrap();
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let b: i64 = c[2].parse().unwrap();
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(enabled, result + if enabled { a * b } else { 0 })
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}
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}
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})
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.1
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}
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#[cfg(test)]
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mod test {
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use super::{part1, part2};
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const TEST_INPUT: &str =
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r"xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))";
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const TEST_INPUT2: &str =
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r"xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))";
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#[test]
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fn test1() {
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assert_eq!(part1(TEST_INPUT), 161);
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}
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#[test]
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fn test2() {
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assert_eq!(part2(TEST_INPUT2), 48);
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}
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}
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