day3, part2

day03/src/main.rs

@@ -8,24 +8,65 @@ use winnow::{
 fn main() {
     let input = std::fs::read_to_string("input").unwrap();
     println!("{}", pt1(&input));
+    println!("{}", pt2(&input));
 }
 
 #[derive(Debug, PartialEq, Eq)]
 enum Inst {
-    Mul(i32, i32),
+    Mul(i64, i64),
+    Do,
+    Dont,
 }
 
-fn pt1(input: &str) -> i32 {
+fn pt1(input: &str) -> i64 {
     let mut input = input;
     let v = parse(&mut input).unwrap();
-    v.iter().map(|Inst::Mul(a, b)| (a * b)).sum()
+    v.iter()
+        .map(|inst| match inst {
+            Inst::Mul(a, b) => a * b,
+            _ => 0,
+        })
+        .sum()
+}
+
+fn pt2(input: &str) -> i64 {
+    let mut input = input;
+    let instructions = parse(&mut input).unwrap();
+    let mut doo = true;
+    let mut total = 0;
+    for i in &instructions {
+        match i {
+            Inst::Do => doo = true,
+            Inst::Dont => doo = false,
+            Inst::Mul(a, b) => {
+                if doo {
+                    total += a * b;
+                }
+            }
+        }
+    }
+    total
+}
+
+fn parse_mul(input: &mut &str) -> PResult<Inst> {
+    let _ = "mul".parse_next(input)?;
+    let pair: (i64, i64) =
+        delimited('(', separated_pair(dec_int, ',', dec_int), ')').parse_next(input)?;
+    Ok(Inst::Mul(pair.0, pair.1))
+}
+
+fn parse_do(input: &mut &str) -> PResult<Inst> {
+    let _ = "do()".parse_next(input)?;
+    Ok(Inst::Do)
+}
+
+fn parse_dont(input: &mut &str) -> PResult<Inst> {
+    let _ = "don't()".parse_next(input)?;
+    Ok(Inst::Dont)
 }
 
 fn parse_inst(input: &mut &str) -> PResult<Inst> {
-    let _ = "mul".parse_next(input)?;
-    let pair: (i32, i32) =
-        delimited('(', separated_pair(dec_int, ',', dec_int), ')').parse_next(input)?;
-    Ok(Inst::Mul(pair.0, pair.1))
+    alt((parse_mul, parse_do, parse_dont)).parse_next(input)
 }
 
 fn parse(input: &mut &str) -> PResult<Vec<Inst>> {
@@ -50,11 +91,18 @@ fn parse(input: &mut &str) -> PResult<Vec<Inst>> {
 mod test {
     use super::*;
 
-    static INPUT: &str = "xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))";
+    static INPUT1: &str = "xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))";
+    static INPUT2: &str =
+        "xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))";
 
     #[test]
     fn p1() {
-        let v = pt1(INPUT);
+        let v = pt1(INPUT1);
         assert_eq!(v, 161)
     }
+
+    #[test]
+    fn p2() {
+        assert_eq!(48, pt2(INPUT2));
+    }
 }