84 lines
2.1 KiB
Rust
84 lines
2.1 KiB
Rust
use std::error::Error;
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use std::fs::File;
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use std::io::{self, BufRead};
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use std::vec::Vec;
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enum SyntaxPoints {
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Corrupted(u64),
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Incomplete(u64),
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}
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fn check_syntax(line: &str) -> SyntaxPoints {
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let mut stack: Vec<char> = Vec::new();
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for c in line.chars() {
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match c {
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'[' => stack.push('['),
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'(' => stack.push('('),
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'{' => stack.push('{'),
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'<' => stack.push('<'),
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']' => {
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if stack.pop() != Some('[') {
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return SyntaxPoints::Corrupted(57);
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}
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}
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')' => {
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if stack.pop() != Some('(') {
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return SyntaxPoints::Corrupted(3);
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}
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}
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'}' => {
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if stack.pop() != Some('{') {
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return SyntaxPoints::Corrupted(1197);
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}
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}
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'>' => {
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if stack.pop() != Some('<') {
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return SyntaxPoints::Corrupted(25137);
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}
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}
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_ => panic!("Unknown char {}", c),
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}
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}
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let mut points = 0;
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for c in stack.iter().rev() {
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match c {
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'(' => points = points * 5 + 1,
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'[' => points = points * 5 + 2,
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'{' => points = points * 5 + 3,
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'<' => points = points * 5 + 4,
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_ => panic!("Unknown char {}", c),
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}
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}
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SyntaxPoints::Incomplete(points)
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}
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fn main() -> Result<(), Box<dyn Error>> {
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let file = File::open("inputs/day10.txt")?;
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let lines: Vec<String> = io::BufReader::new(file)
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.lines()
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.map(|l| l.unwrap())
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.collect();
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let mut answer1 = 0;
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let mut incompletes: Vec<u64> = Vec::new();
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for line in lines.iter() {
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match check_syntax(line) {
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SyntaxPoints::Corrupted(p) => answer1 += p,
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SyntaxPoints::Incomplete(p) => incompletes.push(p),
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}
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}
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println!("Answer1: {}", answer1);
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incompletes.sort();
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println!("Answer2: {}", incompletes[incompletes.len() / 2]);
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Ok(())
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}
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