【链表 - LeetCode】146. LRU 缓存

146. LRU 缓存

题解：

class LRUCache {
    list<pair<int,int>>v;
    unordered_map<int,list<pair<int,int>>::iterator>idx;
    int capacity;
public:
    LRUCache(int capacity):capacity(capacity){}
    
    int get(int key) {
        if(idx.count(key) == 0) return -1;
        v.splice(v.begin(), v, idx[key]);
        return v.front().second;
    }
    
    void put(int key, int value) {
        if(idx.count(key)){
            v.splice(v.begin(),v,idx[key]);
            v.front().second = value;
        }
        else{
            v.emplace_front(key,value);
            idx[key] = v.begin();
        }
        if(v.size() > capacity){
            idx.erase(v.back().first);
            v.pop_back();
        }
    }
};

/**
 * 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);
 */