solution: day 3

src/days.rs

@@ -1,6 +1,6 @@
 pub mod d1;
 pub mod d2;
-// pub mod d3;
+pub mod d3;
 // pub mod d4;
 // pub mod d5;
 // pub mod d6;

src/days/d3.rs

@@ -0,0 +1,102 @@
+#![allow(unused_imports)]
+use crate::prelude::*;
+
+pub type I = &'static str;
+pub type O = u64;
+
+fn _silver (data: I) -> O {
+    let mut sum = 0;
+
+    let mut data = data;
+
+    while let Some(f) = data.find("mul(") {
+        data = &data[f..];
+        let start = 4;
+        let Some(fin) = data.find(')') else { break };
+        let inside = &data[start..fin];
+        if let Some((left, right)) = inside.split_once(',') {
+            if let Ok(left) = left.parse::<u64>() && let Ok(right) = right.parse::<u64>() {
+                sum += left * right;
+            } else {
+                data = &data[start..];
+                continue;
+            }
+        } else {
+            data = &data[start..];
+            continue;
+        }
+        data = &data[fin+1..];
+    }
+    sum
+}
+
+fn _gold (data: I) -> O {
+    let mut sum = 0;
+    let mut enabled = true;
+    let mut data = data;
+
+    loop {
+        let mul = data.find("mul(").unwrap_or(usize::MAX);
+        let _do = data.find("do()").unwrap_or(usize::MAX);
+        let dont = data.find("don't()").unwrap_or(usize::MAX);
+
+        if [mul, _do, dont].iter().all(|&e| e == usize::MAX) {
+            break;
+        }
+
+        let next = mul.min(_do).min(dont);
+
+        if next == mul {
+            data = &data[next..];
+            let start = 4;
+            let Some(fin) = data.find(')') else { break };
+            let inside = &data[start..fin];
+            if let Some((left, right)) = inside.split_once(',') {
+                if let Ok(left) = left.parse::<u64>() && let Ok(right) = right.parse::<u64>() {
+                    if enabled {
+                        sum += left * right;
+                    }
+                } else {
+                    data = &data[start..];
+                    continue;
+                }
+            } else {
+                data = &data[start..];
+                continue;
+            }
+            data = &data[fin+1..];
+        } else if next == _do {
+            enabled = true;
+            data = &data[next+4..];
+        } else if next == dont {
+            enabled = false;
+            data = &data[next+7..];
+        }
+    }
+    sum
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    fn read () -> &'static str {
+        inc!(3)
+    }
+
+    #[test]
+    fn silver () {
+        let data = read();
+        let ans = _silver(data);
+
+        assert_eq!(ans, 181345830)
+    }
+
+    #[test]
+    fn gold () {
+        let data = read();
+        let ans = _gold(data);
+
+        assert_eq!(ans, 98729041)
+    }
+}

src/lib.rs

@@ -3,6 +3,7 @@
 #![feature(decl_macro)]
 #![feature(iter_array_chunks)]
 #![feature(binary_heap_into_iter_sorted)]
+#![feature(type_alias_impl_trait)]
 
 pub mod days;
 pub mod utils;