Complete day 2

crates/day02/src/input/test.txt

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+forward 5
+down 5
+forward 8
+up 3
+down 8
+forward 2

crates/day02/src/main.rs

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+use anyhow::Result;
+use common::instrument;
+
+const INPUT: &str = include_str!("input/input.txt");
+
+fn solve_part1(input: &str) -> Result<i32> {
+    let lines = input.trim().lines();
+
+    let mut horizontal = 0;
+    let mut depth = 0;
+
+    for line in lines {
+        let mut parts = line.split(" ");
+        let command = parts.next().unwrap();
+        let value = parts.next().unwrap().parse::<i32>()?;
+
+        match command {
+            "forward" => horizontal += value,
+            "up" => depth -= value,
+            "down" => depth += value,
+            _ => panic!("Unknown command: {}", command),
+        }
+    }
+
+    Ok(horizontal * depth)
+}
+
+fn solve_part2(input: &str) -> Result<i32> {
+    let lines: Vec<&str> = input.trim().lines().collect();
+
+    let mut horizontal = 0;
+    let mut depth = 0;
+    let mut aim = 0;
+
+    for line in lines {
+        let mut parts = line.split(" ");
+        let command = parts.next().unwrap();
+        let value = parts.next().unwrap().parse::<i32>()?;
+
+        match command {
+            "forward" => {
+                horizontal += value;
+                depth += aim * value;
+            }
+            "up" => aim -= value,
+            "down" => aim += value,
+            _ => panic!("Unknown command: {}", command),
+        }
+    }
+
+    Ok(horizontal * depth)
+}
+
+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(), 150);
+    }
+
+    #[test]
+    fn solves_part2() {
+        assert_eq!(solve_part2(TEST_INPUT).unwrap(), 900);
+    }
+}