sublist

rust/sublist/src/lib.rs

@@ -0,0 +1,40 @@
+#[derive(Debug, PartialEq, Eq)]
+pub enum Comparison {
+    Equal,
+    Sublist,
+    Superlist,
+    Unequal,
+}
+
+trait SublistSearcher<T> {
+    fn contains_slice(&self, sublist: &[T]) -> bool;
+}
+
+impl<T> SublistSearcher<T> for [T]
+where
+    T: PartialEq,
+{
+    fn contains_slice(&self, sublist: &[T]) -> bool {
+        self.is_empty() && sublist.is_empty()
+            || (!sublist.is_empty() && self.windows(sublist.len()).any(|x| x == sublist))
+    }
+}
+
+pub fn sublist(first_list: &[i32], second_list: &[i32]) -> Comparison {
+    match (first_list.len(), second_list.len()) {
+        (len_1, len_2) if len_1 == len_2 && first_list == second_list => Comparison::Equal,
+        (len_1, len_2)
+            if second_list.is_empty() && !first_list.is_empty()
+                || (len_1 > len_2 && first_list.contains_slice(second_list)) =>
+        {
+            Comparison::Superlist
+        }
+        (len_1, len_2)
+            if first_list.is_empty() && !second_list.is_empty()
+                || (len_1 < len_2 && second_list.contains_slice(first_list)) =>
+        {
+            Comparison::Sublist
+        }
+        _ => Comparison::Unequal,
+    }
+}