docs: add some documentation in lru cache

Author: bujosa

src/main.rs

@@ -1,22 +1,14 @@
 mod medium;
 
-use medium::reorder_list::ListNode;
-
 fn main() {
-    // Reorder List - Medium
-    let mut head = Some(Box::new(
-        ListNode::new(1).add_next(
-            ListNode::new(2)
-                .add_next(ListNode::new(3).add_next(ListNode::new(4).add_next(ListNode::new(5)))),
-        ),
-    ));
-
-    medium::reorder_list::reorder_list(&mut head);
-
-    // Print elements of the list
-    let mut curr = head;
-    while let Some(node) = curr {
-        println!("{}", node.val);
-        curr = node.next;
-    }
+    let mut cache = medium::lru_cache::LRUCache::new(2);
+    cache.put(1, 1);
+    cache.put(2, 2);
+    println!("{}", cache.get(1)); // returns 1
+    cache.put(3, 3); // evicts key 2
+    println!("{}", cache.get(2)); // returns -1 (not found)
+    cache.put(4, 4); // evicts key 1
+    println!("{}", cache.get(1)); // returns -1 (not found)
+    println!("{}", cache.get(3)); // returns 3
+    println!("{}", cache.get(4)); // returns 4
 }

src/medium/lru_cache.rs

@@ -23,6 +23,7 @@ impl ListNode {
     }
 }
 
+/// A struct representing a doubly linked list node.
 #[derive(Debug)]
 struct DoubleListNode {
     head: Option<Rc<RefCell<ListNode>>>,
@@ -202,6 +203,13 @@ impl LRUCache {
     }
 }
 
+/*
+    Algorithm - Using a doubly linked list and a hashmap
+
+    Time    O(1)
+    Space   O(n)
+*/
+
 #[cfg(test)]
 mod tests {
     use super::*;