day8: avoid having to manually define all the cmp traits

src/day8.rs

@@ -138,28 +138,12 @@ fn part2(input: &Circuits) -> u64 {
     panic!()
 }
 
+#[derive(PartialEq, Eq, PartialOrd, Ord)]
 struct JunctionPair {
+    d: u64,
     a: usize,
     b: usize,
-    d: u64,
 }
-impl Eq for JunctionPair {}
-impl PartialEq for JunctionPair {
-    fn eq(&self, other: &Self) -> bool {
-        self.d == other.d
-    }
-}
-impl PartialOrd for JunctionPair {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.d.cmp(&other.d))
-    }
-}
-impl Ord for JunctionPair {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        self.d.cmp(&other.d)
-    }
-}
-
 fn make_heap(circuits: &Circuits) -> BinaryHeap<Reverse<JunctionPair>> {
     BinaryHeap::from_iter(
         circuits