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LRU的实现

#include<queue>
#include<iostream>
#include<list>
#include<unordered_map>
using namespace std;

class LRUCache {
public:
    list<pair<int,int> >que;
    unordered_map<int, list<pair<int,int> >::iterator>mp;
    int cap;
    LRUCache(int capacity) {
        que.clear();
        mp.clear();
        cap = capacity;
    }
    
    int get(int key) {
        if (mp.find(key) == mp.end()) return -1;
        list<pair<int,int> >::iterator ptr= mp.find(key)->second;
        int res = ptr->second;
        pair<int,int>newValue(ptr->first,ptr->second);
        que.erase(ptr);
        que.push_front(newValue);
        mp[key] = que.begin();
        return res;
    }
    
    void put(int key, int value) {
        unordered_map<int, list<pair<int,int> >::iterator>::iterator it = mp.find(key);
        if (it != mp.end()) {
            que.erase(it->second);
            que.push_front(make_pair(key,value));
            mp[key] = que.begin();
            return;
        } else if (que.size() < cap) {
            que.push_front(make_pair(key,value));
            mp[key] = que.begin();
            return;
        }
        int endKey = que.back().first;
        unordered_map<int, list<pair<int,int> >::iterator>::iterator endIt = mp.find(endKey);
        mp.erase(endIt);
        que.pop_back();
        que.push_front(make_pair(key,value));
        mp[key] = que.begin();
    }
};

/**
 * 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);
 */

LRU的基本实现 map+双向链表