【Leetocode | 001】146. LRU 缓存机制

146. LRU 缓存机制

1. 题解

class LRUCache {
public:
    LRUCache(int capacity) {
        cap = capacity;
    }
    
    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;
    }
    
    void put(int key, int value) {
        auto iter = m.find(key);
        if(iter != m.end()) l.erase(iter->second);
        l.push_front(make_pair(key, value));
        m[key] = l.begin();
        
        if(m.size() > cap)
        {
            auto it = l.rbegin();
            m.erase(it->first);
            
            l.pop_back();
        }
    }
    private:
    int cap;
    list<pair<int, int>> l;
    unordered_map<int, list<pair<int,int>>::iterator> m;      
};

/**
 * Your LRUCache object will be instantiated and called as such:
 * LRUCache* obj = new LRUCache(capacity);
 * int param_1 = obj->get(key);
 * obj->put(key,value);
 */