146

Author: Ashish-kumar7

146.cpp

@@ -0,0 +1,43 @@
+class LRUCache {
+private:
+    unordered_map<int, pair<int, list<int>::iterator>> cacheObj; 
+    list<int> LRUObj; 
+    int capacity_;
+    
+public:
+    LRUCache(int capacity) {
+        capacity_ = capacity;
+    }
+
+    void useItem(unordered_map<int, pair<int, list<int>::iterator>>::iterator& iter) {
+        LRUObj.erase(iter->second.second);
+        LRUObj.push_front(iter->first);
+        iter->second.second = LRUObj.begin();
+    }
+
+    int get(int key) {
+        auto iter = cacheObj.find(key);
+        if (iter == cacheObj.end()) {
+            return -1;
+        }
+        useItem(iter);
+        return iter->second.first;
+    }
+    
+    void put(int key, int value) {
+        // If the key exists
+        auto iter = cacheObj.find(key);
+        if (iter != cacheObj.end()) {
+            useItem(iter);
+            cacheObj[key] = {value, LRUObj.begin()};
+            return;
+        }
+        if (capacity_ == cacheObj.size()) {
+            cacheObj.erase(LRUObj.back());
+            LRUObj.pop_back();
+        }
+        LRUObj.push_front(key);
+        cacheObj.insert({key, {value, LRUObj.begin()}});
+        return;
+    }
+};