Create 146. LRU Cache.cpp

Author: fengvyi

C++/146. LRU Cache.cpp

@@ -0,0 +1,40 @@
+class LRUCache {
+public:
+    LRUCache(int capacity) {
+        this->capacity = capacity;
+    }
+    
+    int get(int key) {
+        if(!m.count(key) || m[key] == -1) return -1;
+        q.push_back(key);
+        visited[key]++;
+        return m[key];
+    }
+    
+    void put(int key, int value) {
+        if(!m.count(key)|| m[key] == -1) count++;
+        else visited[key]++;
+        if(count > capacity){
+            while(visited[q.front()]) visited[q.front()]--, q.pop_front();
+            m[q.front()] = -1;
+            q.pop_front();
+            count--;
+        }
+        q.push_back(key);
+        m[key] = value;
+    }
+
+private:
+    unordered_map<int, int>m;
+    unordered_map<int, int>visited;
+    deque<int>q;
+    int count = 0;
+    int capacity = 0;
+};
+
+/**
+ * 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);
+ */