标签：des style blog color io os for sp div
Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and set.
get(key) - Get the value (will always be positive) of the key if the key exists in the cache, otherwise return -1.set(key, value) - Set or insert the value if the key is not already present. When the cache reached its capacity, it should invalidate the least recently used item before inserting a new item.
双向链表 + hash map
1 class LRUCache{ 2 public: 3 LRUCache(int capacity) { 4 this->capacity = capacity; 5 } 6 7 int get(int key) { 8 if (cache_map.find(key) != cache_map.end()) { 9 cache_list.splice(cache_list.begin(), cache_list, cache_map[key]); 10 cache_map[key] = cache_list.begin(); 11 return cache_map[key]->value; 12 } else { 13 return -1; 14 } 15 } 16 17 void set(int key, int value) { 18 if (cache_map.find(key) != cache_map.end()) { 19 cache_list.splice(cache_list.begin(), cache_list, cache_map[key]); 20 cache_map[key] = cache_list.begin(); 21 cache_map[key]->value = value; 22 } else { 23 if (cache_list.size() == capacity) { 24 cache_map.erase(cache_list.back().key); 25 cache_list.pop_back(); 26 } 27 cache_list.push_front(cacheNode(key, value)); 28 cache_map[key] = cache_list.begin(); 29 } 30 } 31 private: 32 struct cacheNode { 33 int key; 34 int value; 35 cacheNode(int key, int value) : key(key), value(value) {} 36 }; 37 38 int capacity; 39 unordered_map<int, list<cacheNode>::iterator> cache_map; 40 list<cacheNode> cache_list; 41 };
标签：des style blog color io os for sp div
原文地址：http://www.cnblogs.com/dengeven/p/4004020.html
