Create 146.LRU-Cache.cpp

Design/146.LRU-Cache/146.LRU-Cache.cpp

@@ -0,0 +1,58 @@
+class LRUCache {
+    unordered_map<int,int>Map;
+    list<int>List;
+    unordered_map<int,list<int>::iterator>iter;
+    int cap;
+
+public:
+    LRUCache(int capacity) 
+    {
+        cap=capacity;
+    }
+
+    int get(int key) 
+    {
+        if (Map.find(key)==Map.end()) return -1;
+
+        List.erase(iter[key]);
+        List.push_back(key);
+        iter[key]=--List.end();        
+        return Map[key];
+    }
+
+    void put(int key, int value) 
+    {
+        if (cap<=0) return;
+        if (get(key)!=-1)
+        {
+            Map[key]=value;
+            return;
+        }
+
+        if (List.size()<cap)
+        {
+            List.push_back(key);
+            iter[key]=--List.end();
+            Map[key]=value;
+        }
+        else
+        {
+            int minKey = List.front();
+            iter.erase(minKey);
+            List.pop_front();
+            Map.erase(minKey);
+
+            List.push_back(key);
+            iter[key]=--List.end();
+            Map[key]=value;
+        }
+
+    }
+};
+
+/**
+ * Your LRUCache object will be instantiated and called as such:
+ * LRUCache obj = new LRUCache(capacity);
+ * int param_1 = obj.get(key);
+ * obj.put(key,value);
+ */