Solve day 10!

source/day_10/mod.rs

@@ -0,0 +1,91 @@
+use std::collections::VecDeque;
+
+use color_eyre::Result;
+
+pub fn solve() -> Result<()> {
+  let input_data = include_str!("../../data/day_10.txt").trim();
+  println!("Day 10 Part 1: {}", part_1(input_data)?);
+  println!("Day 10 Part 2: {}", part_2(input_data)?);
+  Ok(())
+}
+
+fn part_1(input: &str) -> Result<usize> {
+  let mut syntax_error_score = 0;
+
+  for line in input.lines() {
+    let mut tokens = VecDeque::new();
+
+    for token in line.chars() {
+      if ['(', '[', '{', '<'].contains(&token) {
+        tokens.push_back(token);
+        continue;
+      }
+
+      let expected_close = match tokens.pop_back() {
+        Some('(') => ')',
+        Some('[') => ']',
+        Some('{') => '}',
+        Some('<') => '>',
+        _ => unreachable!(),
+      };
+
+      if token != expected_close {
+        syntax_error_score += match token {
+          ')' => 3,
+          ']' => 57,
+          '}' => 1197,
+          '>' => 25137,
+          _ => unreachable!(),
+        };
+      }
+    }
+  }
+
+  Ok(syntax_error_score)
+}
+
+fn part_2(input: &str) -> Result<isize> {
+  let mut scores = vec![];
+
+  'line_loop: for line in input.lines() {
+    let mut line_score = 0;
+    let mut tokens = VecDeque::new();
+
+    for token in line.chars() {
+      if ['(', '[', '{', '<'].contains(&token) {
+        tokens.push_back(token);
+        continue;
+      }
+
+      let expected_close = match tokens.pop_back() {
+        Some('(') => ')',
+        Some('[') => ']',
+        Some('{') => '}',
+        Some('<') => '>',
+        _ => unreachable!(),
+      };
+
+      if token != expected_close {
+        continue 'line_loop;
+      }
+    }
+
+    for token in tokens.into_iter().rev() {
+      let token_score = match token {
+        '(' => 1,
+        '[' => 2,
+        '{' => 3,
+        '<' => 4,
+        _ => unreachable!(),
+      };
+
+      line_score *= 5;
+      line_score += token_score;
+    }
+
+    scores.push(line_score);
+  }
+
+  scores.sort_by(|a, b| a.cmp(b));
+  Ok(scores[scores.len() / 2])
+}

source/main.rs

@@ -11,6 +11,7 @@ mod day_06;
 mod day_07;
 mod day_08;
 mod day_09;
+mod day_10;
 
 fn main() -> Result<()> {
   color_eyre::install()?;
@@ -27,6 +28,7 @@ fn main() -> Result<()> {
     day_07::solve,
     day_08::solve,
     day_09::solve,
+    day_10::solve,
   ];
 
   for day in days {