solution: day 7

src/days.rs

@@ -4,7 +4,7 @@ pub mod d3;
 pub mod d4;
 pub mod d5;
 pub mod d6;
-// pub mod d7;
+pub mod d7;
 // pub mod d8;
 // pub mod d9;
 // pub mod d10;

src/days/d7.rs

@@ -0,0 +1,62 @@
+use crate::prelude::*;
+
+pub type I = Vec<(u64, Vec<u64>)>;
+pub type O = u64;
+
+fn _parse (data: &str) -> I {
+    data.trim().lines().map(|e| e.trim().split_once(": ").map(|(left, right)| (p!(left), right.split_ascii_whitespace().map(|e| p!(e)).collect())).unwrap()).collect()
+}
+
+fn _solve (data: I, consider_concats: bool) -> O {
+    data.iter().filter(|(val, list)| {
+        let mut results: S<u64> = S::from([list[0]]);
+        for &i in &list[1..] {
+            for p in results.drain().collect_vec() {
+                let prod = i * p;
+                let sum = i + p;
+                if prod <= *val { results.insert(prod); }
+                if sum <= *val { results.insert(sum); }
+
+                if consider_concats {
+                    let concat = p * 10u64.pow(i.ilog10() + 1) + i;
+                    if concat <= *val { results.insert(concat); }
+                }
+            }
+        }
+        results.contains(val)
+    }).map(|(val, _)| val).sum()
+}
+
+fn _silver (data: I) -> O {
+    _solve(data, false)
+}
+
+fn _gold (data: I) -> O {
+    _solve(data, true)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    fn read () -> I {
+        let data = inc!(7);
+        _parse(data)
+    }
+
+    #[test]
+    fn silver () {
+        let data = read();
+        let ans = _silver(data);
+
+        assert_eq!(ans, 5837374519342)
+    }
+
+    #[test]
+    fn gold () {
+        let data = read();
+        let ans = _gold(data);
+
+        assert_eq!(ans, 492383931650959)
+    }
+}