101 lines
2.6 KiB
Rust
101 lines
2.6 KiB
Rust
#![feature(test)]
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extern crate test;
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use aoc2021::common::*;
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const DAY: usize = 10;
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fn solve(input: &str) -> (usize, usize) {
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let mut p1_score = 0;
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let mut p2_scores = Vec::new();
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let mut stack = Vec::new();
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for line in input.lines() {
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match is_well_formed(line, &mut stack) {
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Ok(s) => p2_scores.push(autocomplete_points(s)), // <- clears the stack internally
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Err(p) => {
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p1_score += p;
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stack.clear();
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}
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}
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}
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let p2_len = p2_scores.len();
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(p1_score, *p2_scores.select_nth_unstable(p2_len / 2).1)
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}
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fn is_well_formed<'a>(line: &str, stack: &'a mut Vec<u8>) -> Result<&'a mut Vec<u8>, usize> {
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for c in line.bytes() {
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match (stack.last(), c) {
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(_, b'(' | b'[' | b'<' | b'{') => stack.push(c),
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(Some(b'('), b')') | (Some(b'['), b']') | (Some(b'{'), b'}') | (Some(b'<'), b'>') => {
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stack.pop();
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}
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(_, b')') => return Err(3),
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(_, b']') => return Err(57),
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(_, b'}') => return Err(1197),
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(_, b'>') => return Err(25137),
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_ => unreachable!(),
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}
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}
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Ok(stack)
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}
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fn autocomplete_points(stack: &mut Vec<u8>) -> usize {
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let mut points = 0;
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for p in stack.drain(..).rev() {
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points *= 5;
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match p {
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b'(' => points += 1,
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b'[' => points += 2,
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b'{' => points += 3,
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b'<' => points += 4,
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_ => unreachable!(),
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}
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}
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points
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}
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fn main() {
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let raw = read_file(DAY);
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let (p1, p2) = solve(&raw);
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println!("Part 1: {p1}");
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println!("Part 2: {p2}");
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use aoc2021::*;
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const TEST_INPUT: &str = "[({(<(())[]>[[{[]{<()<>>
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[(()[<>])]({[<{<<[]>>(
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{([(<{}[<>[]}>{[]{[(<()>
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(((({<>}<{<{<>}{[]{[]{}
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[[<[([]))<([[{}[[()]]]
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[{[{({}]{}}([{[{{{}}([]
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{<[[]]>}<{[{[{[]{()[[[]
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[<(<(<(<{}))><([]([]()
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<{([([[(<>()){}]>(<<{{
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<{([{{}}[<[[[<>{}]]]>[]]";
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#[bench]
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fn bench_autocomplete_points(b: &mut test::Bencher) {
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let sample_stack = vec![b'<', b'{', b'(', b'['];
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b.iter(|| assert_eq!(autocomplete_points(test::black_box(&mut sample_stack.clone())), 294));
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}
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#[test]
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fn part1_test() {
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assert_eq!(solve(TEST_INPUT).0, 26397);
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}
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#[test]
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fn part2_test() {
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assert_eq!(solve(TEST_INPUT).1, 288957);
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}
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#[bench]
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fn bench_solution(b: &mut test::Bencher) {
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let raw = read_file(DAY);
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b.iter(|| assert_eq!(solve(test::black_box(&raw)), (358737, 4329504793)))
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}
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}
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