Day 3 part 1 done

2024/rust/src/day3.rs

@@ -2,7 +2,58 @@ mod prelude;
 pub use crate::prelude::*;
 
 fn main() {
-    show_answers(0, 0);
+    let input = day_input(3);
+    show_answers(sum_muls(&input), 0);
+}
+
+struct MulParser {
+    left: Option<usize>,
+    right: Option<usize>,
+}
+
+fn sum_muls(input: &str) -> usize {
+    let mut sum = 0;
+    let mut s = &input[..];
+    while let Some(i) = s.find("mul(") {
+        s = &s[i + 4..];
+        let mut left: Option<usize> = None;
+        let mut right: Option<usize> = None;
+        let mut token = &s[0..0];
+        for c in s.chars() {
+            println!("c: {c}");
+            match c {
+                '0'..='9' => {
+                    token = &s[0..token.len() + 1];
+                    if token.len() > 3 {
+                        break;
+                    }
+                }
+                ',' => {
+                    println!("token at , {token:?}");
+                    if left.is_some() {
+                        break;
+                    }
+                    left = Some(token.parse().unwrap());
+                    s = &s[token.len() + 1..];
+                    token = &s[0..0];
+                }
+                ')' => {
+                    println!("token at ) {token:?}");
+                    if right.is_some() {
+                        break;
+                    }
+                    right = Some(token.parse().unwrap());
+                    s = &s[token.len() + 1..];
+                    token = &s[0..0];
+                }
+                _ => break,
+            }
+        }
+        if let (Some(left), Some(right)) = (left, right) {
+            sum += left * right;
+        }
+    }
+    return sum;
 }
 
 #[cfg(test)]
@@ -10,5 +61,10 @@ mod tests {
     use super::*;
 
     #[test]
-    fn test() {}
+    fn test() {
+        assert_eq!(
+            sum_muls("xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))"),
+            161
+        )
+    }
 }

2024/rust/src/template.rs

@@ -2,6 +2,7 @@ mod prelude;
 pub use crate::prelude::*;
 
 fn main() {
+    let _input = day_input(0);
     show_answers(0, 0);
 }