LRU Cache的C++实现

来源：互联网发布：ember.js入门教程编辑：程序博客网时间：2024/05/18 00:55

方法一：双链表+哈希表map

#include<iostream>#include<map>using namespace std;struct Node{    int key;    int value;    Node* pre;    Node* next;    Node(int key=-1,int value=-1):key(key),value(value),pre(NULL),next(NULL){};};class Solution{private:    int capacity;    Node* head;    Node* tail;    map<int,Node*>cachemp;public:    Solution(int size=5);    ~Solution();    void deletenode(Node* node);    void putfront(Node* node);    int get(int key);    void set(int key,int value);    void display();    void showmap();};Solution::Solution(int size){    capacity=size;    head=new Node;    tail=new Node;    head->next=tail;    head->pre=NULL;    tail->pre=head;    tail->next=NULL;}Solution::~Solution(){    Node* p;    p=head->next;    while(p)    {        delete(p->pre);        p=p->next;    }    delete(tail);} void Solution::putfront(Node* node){    node->next=head->next;    head->next=node;    node->next->pre=node;    node->pre=head; } void Solution::deletenode(Node* node) {        if(node==NULL)            return;        node->pre->next=node->next;        node->next->pre=node->pre;        delete(node);    } int Solution::get(int key) {     map<int,Node*>::iterator iter=cachemp.find(key);     if(iter==cachemp.end())     {        return -1;     }     else     {          Node* node=new Node(iter->second->key,iter->second->value);        deletenode(iter->second);        cachemp.erase(iter);        putfront(node);        cachemp[key]=node;        return node->value;     }     showmap(); } void Solution::set(int key,int value) {     map<int,Node*>::iterator iter=cachemp.find(key);     Node* node=new Node(key,value);     if(iter==cachemp.end())     {         if(cachemp.size()==capacity)         {                  cachemp.erase(tail->pre->key);            deletenode(tail->pre);                   }               putfront(node);         cachemp[key]=node;      }     else     {         deletenode(iter->second);         putfront(node);          cachemp.erase(iter);         cachemp[key]=head->next;       }     display();      showmap(); } void Solution::display() {    Node* p=head->next;    cout<<"*********"<<endl;    cout<<"realsize="<<cachemp.size()<<endl;    while(p!=tail)    {        cout<<p->key<<' '<<p->value<<endl;        p=p->next;    } } void Solution::showmap() {     cout<<"***"<<endl;     for(map<int,Node*>::iterator iter=cachemp.begin();iter!=cachemp.end();iter++)         cout<<iter->first<<' '<<iter->second->key<<' '<<iter->second->value<<endl; }   void main() {    Solution solution(3);    solution.set(-1,-1);    solution.set(2,2);    solution.set(3,3);       solution.set(4,4);        cout<<"print"<<solution.get(4)<<endl;         cout<<"print"<<solution.get(2)<<endl;    cout<<"print"<<solution.get(3)<<endl;    cout<<"print"<<solution.get(1)<<endl;     solution.set(2,9);    solution.set(3,14);    solution.set(4,11);    solution.set(5,5);       cout<<"print"<<solution.get(1)<<endl;    cout<<"print"<<solution.get(2)<<endl;    cout<<"print"<<solution.get(3)<<endl;    cout<<"print"<<solution.get(4)<<endl;    cout<<"print"<<solution.get(5)<<endl; }

方法二：双链表

#include<iostream>using namespace std;struct Node{    int key;    int value;    Node* pre;    Node* next;    Node(int key=-1,int value=-1):key(key),value(value),pre(NULL),next(NULL){};};class Solution{private:    int capacity;    int realsize;    Node* head;    Node* tail;public:    Solution(int size=10);    ~Solution();    int get(int key);    void set(int key,int value);    void putfront(Node* node);    void deletenode(Node* node);    void display();};Solution::Solution(int size){    realsize=0;    capacity=size;    head=new Node;    tail=new Node;    head->next=tail;    head->pre=NULL;    tail->pre=head;    tail->next=NULL;}Solution::~Solution(){    Node* p;    p=head->next;    while(p)    {        delete(p->pre);        p=p->next;    }    delete(tail);} void Solution::putfront(Node* node){    node->next=head->next;    head->next=node;    node->next->pre=node;    node->pre=head; } void Solution::deletenode(Node* node) {        node->pre->next=node->next;        node->next->pre=node->pre;        delete(node);    } int Solution::get(int key) {    Node* node=head->next;    while(node!=tail)    {        if(node->key==key)        {               Node* node1=new Node(node->key,node->value);            deletenode(node);            putfront(node1);            return node1->value;        }        node=node->next;    }    return -1; } void Solution::set(int key,int value) {    Node* node=head->next;    Node* node1=new Node(key,value);    while(node!=tail)    {        if(node->key==key)        {            deletenode(node);            putfront(node1);            display();            return ;        }        node=node->next;    }    if(realsize==capacity)    {        deletenode(tail->pre);        putfront(node1);    }    else    {        putfront(node1);        realsize++;    }    display(); } void Solution::display() {    Node* p=head->next;    cout<<"*********"<<endl;    cout<<"realsize="<<realsize<<endl;    while(p!=tail)    {        cout<<p->key<<' '<<p->value<<endl;        p=p->next;    } } void main() {    Solution solution(3);    solution.set(-1,-1);    solution.set(2,2);    solution.set(3,3);       solution.set(4,4);        cout<<"print"<<solution.get(4)<<endl;         cout<<"print"<<solution.get(2)<<endl;    cout<<"print"<<solution.get(3)<<endl;    cout<<"print"<<solution.get(1)<<endl;     solution.set(2,9);    solution.set(3,14);    solution.set(5,5);       cout<<"print"<<solution.get(1)<<endl;    cout<<"print"<<solution.get(2)<<endl;    cout<<"print"<<solution.get(3)<<endl;    cout<<"print"<<solution.get(4)<<endl;    cout<<"print"<<solution.get(5)<<endl; }

方法三:双链表+哈希表map

#include<iostream>#include<map>#include<list>using namespace std;struct Node{    int key;    int value;    Node(int key=-1,int value=-1):key(key),value(value){}};class cache{private:    int capacity;    list<Node>listnode;    map<int,list<Node>::iterator>cachelist;    void display();public:    cache(int num):capacity(num){};    int get(int);    void set(int key,int value);};void cache::set(int key,int value){        Node node;        map<int,list<Node>::iterator>::iterator iter=cachelist.find(key);        if(iter==cachelist.end())               {            if(cachelist.size()==capacity)            {                           cachelist.erase(cachelist.find(listnode.back().key));                listnode.pop_back();                    }            node.key=key;            node.value=value;            listnode.push_front(node);            cachelist[key]=listnode.begin();        }        else        {                       listnode.erase(iter->second);                   node.key=key;            node.value=value;            listnode.push_front(node);            cachelist[key]=listnode.begin();        }           display();}int cache::get(int key){        Node *node=new Node;        map<int,list<Node>::iterator>::iterator iter=cachelist.find(key);        if(iter==cachelist.end())        {            return -1;                  }        else        {                               node->key=key;            node->value=iter->second->value;                listnode.erase(iter->second);            listnode.push_front(*node);            cachelist.erase(iter);            cachelist[key]=listnode.begin();        }        display();        return node->value;}void cache::display(){    cout<<"*******"<<endl;    for(list<Node>::iterator it=listnode.begin();it!=listnode.end();it++)        cout<<it->key<<' '<<it->value<<endl;    cout<<"###"<<endl;    for(map<int,list<Node>::iterator>::iterator ti=cachelist.begin();ti!=cachelist.end();ti++)        cout<<ti->first<<' '<<cachelist[ti->first]->key<<' '<<cachelist[ti->first]->value<<endl;}void main(){    cache Cache(3);    Cache.set(1,1);    Cache.set(2,2);        Cache.set(3,3);      Cache.set(4,4);       cout<<"print"<<Cache.get(4)<<endl;        cout<<"print"<<Cache.get(2)<<endl;    cout<<"print"<<Cache.get(3)<<endl;    cout<<"print"<<Cache.get(1)<<endl;    Cache.set(2,9);    Cache.set(3,14);    Cache.set(4,11);    Cache.set(5,5);       cout<<"print"<<Cache.get(1)<<endl;    cout<<"print"<<Cache.get(2)<<endl;    cout<<"print"<<Cache.get(3)<<endl;    cout<<"print"<<Cache.get(4)<<endl;    cout<<"print"<<Cache.get(5)<<endl;    }

0 0