1 struct Node { 2 int key, value; 3 Node(int k, int v) : key(k), value(v) {} 4 }; 5 6 class LRUCache{ 7 private: 8 int size; 9 list<Node> nlist; 10 unordered_map<int, list<Node>::iterator> nmap; 11 public: 12 LRUCache(int capacity) { 13 size = capacity; 14 } 15 16 int get(int key) { 17 if (nmap.find(key) != nmap.end()) { 18 nlist.splice(nlist.begin(), nlist, nmap[key]); 19 nmap[key] = nlist.begin(); 20 return nlist.begin()->value; 21 } 22 return -1; 23 } 24 25 void set(int key, int value) { 26 if (nmap.find(key) == nmap.end()) { 27 if (size == nlist.size()) { 28 nmap.erase(nlist.back().key); 29 nlist.pop_back(); 30 } 31 nlist.push_front(Node(key, value)); 32 nmap[key] = nlist.begin(); 33 } else { 34 nlist.splice(nlist.begin(), nlist, nmap[key]); 35 nmap[key] = nlist.begin(); 36 nlist.begin()->value = value; 37 } 38 } 39 };
