solution: day 5

src/days.rs

@@ -2,7 +2,7 @@ pub mod d1;
 pub mod d2;
 pub mod d3;
 pub mod d4;
-// pub mod d5;
+pub mod d5;
 // pub mod d6;
 // pub mod d7;
 // pub mod d8;

src/days/d5.rs

@@ -0,0 +1,108 @@
+use crate::prelude::*;
+
+pub type I = (M<u32, S<u32>>, Vec<Vec<u32>>);
+pub type O = u32;
+
+fn _parse (data: &str) -> I {
+    data.trim().split_once("\n\n").map(|(left, right)| {
+        let mut m: M<u32, S<u32>> = M::new();
+
+        left.trim().lines().for_each(|line| {
+            let (x, y) = line.trim().split_once('|').unwrap();
+            let x = p!(x);
+            let y = p!(y);
+
+            m.entry(x).or_default().insert(y);
+        });
+
+        let v = right.trim().lines().map(|e| e.split(',').map(|e| p!(e)).collect()).collect();
+
+        (m, v)
+    }).unwrap()
+}
+
+
+fn _silver ((rules, list): I) -> O {
+    list.into_iter().filter(|page| {
+        let mut seen = S::new();
+
+        for &n in page {
+            let rules_for_n = rules.get(&n);
+            if let Some(rules) = rules_for_n {
+                if seen.intersection(rules).count() != 0 {
+                    return false;
+                }
+            }
+            seen.insert(n);
+        }
+        true
+    }).map(|page| page[page.len() / 2]).sum()
+}
+
+fn _gold ((rules, list): I) -> O {
+    list.into_iter().filter(|page| {
+        let mut seen = S::new();
+
+        for &n in page {
+            let rules_for_n = rules.get(&n);
+            if let Some(rules) = rules_for_n {
+                if seen.intersection(rules).count() != 0 {
+                    return true;
+                }
+            }
+            seen.insert(n);
+        }
+        false
+    })
+    .map(|mut page| {
+        let mut seen = M::new();
+        let mut ptr = 0;
+
+        'outer : while ptr < page.len() {
+            let n = page[ptr];
+            let rules_for_n = rules.get(&n);
+            if let Some(rules) = rules_for_n {
+                for r in rules {
+                    if let Some(seen_idx) = seen.get(r) {
+                        let removed = page.remove(ptr);
+                        page.insert(*seen_idx, removed);
+                        ptr = 0;
+                        seen.clear();
+                        continue 'outer;
+                    }
+                }
+            }
+            seen.insert(n, ptr);
+            ptr += 1;
+        }
+
+        page
+    })
+    .map(|page| page[page.len() / 2]).sum()
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    fn read () -> I {
+        let data = inc!(5);
+        _parse(data)
+    }
+
+    #[test]
+    fn silver () {
+        let data = read();
+        let ans = _silver(data);
+
+        assert_eq!(ans, 6260)
+    }
+
+    #[test]
+    fn gold () {
+        let data = read();
+        let ans = _gold(data);
+
+        assert_eq!(ans, 5346)
+    }
+}