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.

 

LeetCode上的原题，请参加我之前的博客。

 

class LRUCache{public:    // @param capacity, an integer    LRUCache(int capacity) {        size = capacity;    }        // @return an integer    int get(int key) {        auto it = m.find(key);        if (it == m.end()) return -1;        l.splice(l.begin(), l, it->second);        return it->second->second;    }    // @param key, an integer    // @param value, an integer    // @return nothing    void set(int key, int value) {        auto it = m.find(key);        if (it != m.end()) l.erase(it->second);        l.push_front({key, value});        m[key] = l.begin();        if (m.size() > size) {            int t = l.rbegin()->first;            l.pop_back();            m.erase(t);        }    }private:    int size;    list
     
      
        > l;    unordered_map
       
         >::iterator> m;};