1 files changed, 68 insertions, 0 deletions
diff --git a/aoc/2024/03/rust/src/main.rs b/aoc/2024/03/rust/src/main.rs
new file mode 100644
index 0000000..b268463
--- /dev/null
+++ b/aoc/2024/03/rust/src/main.rs
@@ -0,0 +1,68 @@
+use std::io::{self, Read};
+
+#[derive(Debug)]
+enum Instruction {
+    Do,
+    Dont,
+    Mul(u64, u64),
+}
+
+impl From<&Instruction> for u64 {
+    fn from(val: &Instruction) -> Self {
+        match val {
+            Instruction::Mul(x, y) => x * y,
+            _ => 0,
+        }
+    }
+}
+
+fn main() -> io::Result<()> {
+    let mut program = String::new();
+    io::stdin().read_to_string(&mut program)?;
+
+    let instrs = (0..program.len())
+        .filter_map(|idx| {
+            let next = &program[idx..];
+            if next.starts_with("do()") {
+                Some(Instruction::Do)
+            } else if next.starts_with("don't()") {
+                Some(Instruction::Dont)
+            } else if next.starts_with("mul(") {
+                let mut first = 0;
+                let mut curr = 0;
+
+                for ch in next.bytes().skip(4) {
+                    match (ch, curr) {
+                        ((b'0'..=b'9'), _) => curr = curr * 10 + (ch - b'0') as u64,
+                        (_, 0) => return None,
+                        (b',', _) => {
+                            first = curr;
+                            curr = 0;
+                        }
+                        (b')', _) => {
+                            return Some(Instruction::Mul(first, curr));
+                        }
+                        _ => return None,
+                    };
+                }
+                None
+            } else {
+                None
+            }
+        })
+        .collect::<Vec<_>>();
+
+    let silver: u64 = instrs.iter().map(u64::from).sum();
+    let (gold, _) = instrs
+        .iter()
+        .fold((0 as u64, true), |(acc, on), instr| match (instr, on) {
+            (Instruction::Do, _) => (acc, true),
+            (Instruction::Dont, _) => (acc, false),
+            (Instruction::Mul(_, _), true) => (acc + u64::from(instr), true),
+            _ => (acc, on),
+        });
+    println!("silver: {silver}");
+    println!("gold: {gold}");
+
+    return Ok(());
+}