Complete day 10

2021-12-10 00:34:22 -05:00
parent 39e93eeffa
commit 9b51603a15
5 changed files with 266 additions and 0 deletions
--- a/crates/day10/src/main.rs
+++ b/crates/day10/src/main.rs
@@ -0,0 +1,136 @@
+use anyhow::Result;
+use common::instrument;
+
+const INPUT: &str = include_str!("input/input.txt");
+
+fn solve_part1(input: &str) -> Result<u32> {
+    let lines = input.trim().lines();
+
+    let mut points = 0;
+    for line in lines {
+        let mut opens = vec![];
+
+        for char in line.trim().chars() {
+            match char {
+                '(' | '[' | '{' | '<' => opens.push(char),
+                ')' => {
+                    if let Some(open) = opens.pop() {
+                        if open != '(' {
+                            points += 3;
+                            break;
+                        }
+                    }
+                }
+                ']' => {
+                    if let Some(open) = opens.pop() {
+                        if open != '[' {
+                            points += 57;
+                            break;
+                        }
+                    }
+                }
+                '}' => {
+                    if let Some(open) = opens.pop() {
+                        if open != '{' {
+                            points += 1197;
+                            break;
+                        }
+                    }
+                }
+                '>' => {
+                    if let Some(open) = opens.pop() {
+                        if open != '<' {
+                            points += 25137;
+                            break;
+                        }
+                    }
+                }
+                _ => panic!("unexpected character"),
+            }
+        }
+    }
+
+    Ok(points)
+}
+
+fn solve_part2(input: &str) -> Result<u64> {
+    let lines = input.trim().lines();
+
+    let mut scores = vec![];
+    'lines: for line in lines {
+        let mut opens = vec![];
+        let mut points: u64 = 0;
+
+        for char in line.trim().chars() {
+            match char {
+                '(' | '[' | '{' | '<' => opens.push(char),
+                ')' => {
+                    if let Some(open) = opens.pop() {
+                        if open != '(' {
+                            continue 'lines;
+                        }
+                    }
+                }
+                ']' => {
+                    if let Some(open) = opens.pop() {
+                        if open != '[' {
+                            continue 'lines;
+                        }
+                    }
+                }
+                '}' => {
+                    if let Some(open) = opens.pop() {
+                        if open != '{' {
+                            continue 'lines;
+                        }
+                    }
+                }
+                '>' => {
+                    if let Some(open) = opens.pop() {
+                        if open != '<' {
+                            continue 'lines;
+                        }
+                    }
+                }
+                _ => panic!("unexpected character"),
+            }
+        }
+
+        if !opens.is_empty() {
+            for open in opens.iter().rev() {
+                match open {
+                    '(' => points = (points * 5) + 1,
+                    '[' => points = (points * 5) + 2,
+                    '{' => points = (points * 5) + 3,
+                    '<' => points = (points * 5) + 4,
+                    _ => panic!("unexpected open character"),
+                }
+            }
+            scores.push(points);
+        }
+    }
+
+    scores.sort();
+    Ok(scores[scores.len() / 2])
+}
+
+fn main() {
+    instrument!(solve_part1(INPUT).unwrap(), solve_part2(INPUT).unwrap());
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INPUT: &str = include_str!("input/test.txt");
+
+    #[test]
+    fn solves_part1() {
+        assert_eq!(solve_part1(TEST_INPUT).unwrap(), 26397);
+    }
+
+    #[test]
+    fn solves_part2() {
+        assert_eq!(solve_part2(TEST_INPUT).unwrap(), 288957);
+    }
+}