Merge pull request #351 from kunal164107/master

Added different method for LRU caches Implementation Issue #341

Author: probot-auto-merge[bot]

LRU Cache Implementation/LRU-Cache-Method-2.cpp

@@ -0,0 +1,78 @@
+#include <bits/stdc++.h> 
+using namespace std; 
+  
+class LRUCache { 
+    // store keys of cache 
+    list<int> dq; 
+  
+    // store references of key in cache 
+    unordered_map<int, list<int>::iterator> ma; 
+    int csize; // maximum capacity of cache 
+  
+public: 
+    LRUCache(int); 
+    void refer(int); 
+    void display(); 
+}; 
+  
+// Declare the size 
+LRUCache::LRUCache(int n) 
+{ 
+    csize = n; 
+} 
+  
+// Refers key x with in the LRU cache 
+void LRUCache::refer(int x) 
+{ 
+    // not present in cache 
+    if (ma.find(x) == ma.end()) { 
+        // cache is full 
+        if (dq.size() == csize) { 
+            // delete least recently used element 
+            int last = dq.back(); 
+  
+            // Pops the last elmeent 
+            dq.pop_back(); 
+  
+            // Erase the last 
+            ma.erase(last); 
+        } 
+    } 
+  
+    // present in cache 
+    else
+        dq.erase(ma[x]); 
+  
+    // update reference 
+    dq.push_front(x); 
+    ma[x] = dq.begin(); 
+} 
+  
+// Function to display contents of cache 
+void LRUCache::display() 
+{ 
+  
+    // Iterate in the deque and print 
+    // all the elements in it 
+    for (auto it = dq.begin(); it != dq.end(); 
+         it++) 
+        cout << (*it) << " "; 
+  
+    cout << endl; 
+} 
+  
+// Driver Code 
+int main() 
+{ 
+    LRUCache ca(4); 
+  
+    ca.refer(1); 
+    ca.refer(2); 
+    ca.refer(3); 
+    ca.refer(1); 
+    ca.refer(4); 
+    ca.refer(5); 
+    ca.display(); 
+  
+    return 0; 
+}