refactor 146

fishercoder1534 · fishercoder1534 · commit 9c4db3d88b87 · 2017-09-06T08:19:39.000-07:00
diff --git a/README.md b/README.md
@@ -470,7 +470,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |149|[Max Points on a Line](https://leetcode.com/problems/max-points-on-a-line/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_149.java)| O(?)|O(?) | Hard|
 |148|[Sort List](https://leetcode.com/problems/sort-list/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_148.java) O(nlogn)|O(h) | Medium| Linked List, Sort
 |147|[Insertion Sort List](https://leetcode.com/problems/insertion-sort-list/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_147.java) O(n^2)|O(1) | Medium| Linked List
-|146|[LRU Cache](https://leetcode.com/problems/lru-cache/)|[Solution](../master/leetcode-algorithms/src/main/java/com/fishercoder/solutions/_146.java)| amortized O(1)| O(n) | Hard| Linked List
+|146|[LRU Cache](https://leetcode.com/problems/lru-cache/)|[Solution](../master/leetcode-algorithms/src/main/java/com/fishercoder/solutions/_146.java)| amortized O(1)| O(k) | Hard| Doubly Linked List, LinkedHashMap
 |145|[Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_145.java)| O(n)|O(h) | Hard| Binary Tree
 |144|[Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_144.java)| O(n)|O(h) | Medium| Binary Tree
 |143|[Reorder List](https://leetcode.com/problems/reorder-list/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_143.java)| O(n)|O(1) | Medium|
diff --git a/src/main/java/com/fishercoder/solutions/_146.java b/src/main/java/com/fishercoder/solutions/_146.java
@@ -33,7 +33,7 @@ Could you do both operations in O(1) time complexity?
 
 public class _146 {
 
-    public class LinkedHashMapSolution {
+    public class Solution1 {
         /**
          * The shortest implementation is to use LinkedHashMap:
          * specify a size of the linkedHashMap;
@@ -47,7 +47,7 @@ public class LinkedHashMapSolution {
         private Map<Integer, Integer> cache;
         private final int max;
 
-        public LinkedHashMapSolution(int capacity) {
+        public Solution1(int capacity) {
             max = capacity;
             cache = new LinkedHashMap<Integer, Integer>(capacity, 1.0f, true) {
                 public boolean removeEldestEntry(Map.Entry eldest) {
@@ -65,13 +65,14 @@ public void set(int key, int value) {
         }
     }
 
-    public class DoublyLinkedListPlusHashMapSolution {
+    public class Solution2 {
+        /**The more verbose solution is to write a doubly linked list plus a map.*/
         private class Node {
             int key;
             int value;
 
-            DoublyLinkedListPlusHashMapSolution.Node prev;
-            DoublyLinkedListPlusHashMapSolution.Node next;
+            Solution2.Node prev;
+            Solution2.Node next;
 
             Node(int k, int v) {
                 this.key = k;
@@ -86,24 +87,24 @@ private class Node {
 
         private int capacity;
         private int count;
-        private DoublyLinkedListPlusHashMapSolution.Node head;
-        private DoublyLinkedListPlusHashMapSolution.Node tail;
-        private Map<Integer, DoublyLinkedListPlusHashMapSolution.Node> map;
+        private Solution2.Node head;
+        private Solution2.Node tail;
+        private Map<Integer, Solution2.Node> map;
         // ATTN: the value should be Node type! This is the whole point of having a class called Node!
 
-        public DoublyLinkedListPlusHashMapSolution(int capacity) {
+        public Solution2(int capacity) {
             this.capacity = capacity;
             this.count = 0;// we need a count to keep track of the number of elements in the cache so
             // that we know when to evict the LRU one from the cache
             this.map = new HashMap();
-            head = new DoublyLinkedListPlusHashMapSolution.Node();
-            tail = new DoublyLinkedListPlusHashMapSolution.Node();
+            head = new Solution2.Node();
+            tail = new Solution2.Node();
             head.next = tail;
             tail.prev = head;
         }
 
         public int get(int key) {
-            DoublyLinkedListPlusHashMapSolution.Node node = map.get(key);
+            Solution2.Node node = map.get(key);
             // HashMap allows value to be null, this is superior than HashTable!
             if (node == null) {
                 return -1;
@@ -122,9 +123,9 @@ public int get(int key) {
         }
 
         public void set(int key, int value) {
-            DoublyLinkedListPlusHashMapSolution.Node node = map.get(key);
+            Solution2.Node node = map.get(key);
             if (node == null) {
-                node = new DoublyLinkedListPlusHashMapSolution.Node(key, value);
+                node = new Solution2.Node(key, value);
                 map.put(key, node);
                 add(node);
                 count++;
@@ -133,7 +134,7 @@ public void set(int key, int value) {
                     /** ATTN: It's tail.prev, not tail, because tail is always an invalid node, it
                     doesn't contain anything, it's always the tail.prev that is the last node in the
                     cache*/
-                    DoublyLinkedListPlusHashMapSolution.Node toDelete = tail.prev;
+                    Solution2.Node toDelete = tail.prev;
                     map.remove(toDelete.key);
                     remove(toDelete);
                     count--;
@@ -145,16 +146,16 @@ public void set(int key, int value) {
             }
         }
 
-        private void remove(DoublyLinkedListPlusHashMapSolution.Node node) {
-            DoublyLinkedListPlusHashMapSolution.Node next = node.next;
-            DoublyLinkedListPlusHashMapSolution.Node prev = node.prev;
+        private void remove(Solution2.Node node) {
+            Solution2.Node next = node.next;
+            Solution2.Node prev = node.prev;
             prev.next = next;
             next.prev = prev;
         }
 
-        private void add(DoublyLinkedListPlusHashMapSolution.Node node) {
+        private void add(Solution2.Node node) {
             // ATTN: we'll always add the node into the first position: head.next!!!!
-            DoublyLinkedListPlusHashMapSolution.Node next = head.next;
+            Solution2.Node next = head.next;
             head.next = node;
             node.next = next;
             node.prev = head;
