求链表倒数第四个元素

题目:单向链表的倒数第四个元素

程序:

#include<iostream>

#include<list>

#include<vector>

using namespace std;

 

class ite{

int p;

public:

int operator++();

ite& operator=(int a){p=a;return *this;}

int& v(){return p;}

int minus4();

};

 

class ring{

vector<int> store;

ite pointer;

public:

ring();

bool full(){return (store[0]&&store[1]&&store[2]&&store[3]);}

void add(int a){this->operator[](pointer)=a;++pointer;}

int last4(){pointer.minus4();return this->operator[](pointer);}

int& operator[](ite i){return i.v();}

};

 

int ite::operator++(){

if(p==3)return p=0;

return ++p;

}

int ite::minus4(){

if(p==3)return p=0;

return ++p;

}

 

ring::ring(){

for(int i=0;i<4;++i)store.push_back(0);

pointer=0;

}

 

int main(){

list<int> li;

int temp;

while(cin>>temp)li.push_back(temp);

ring ri;

for(list<int>::iterator i=li.begin();i!=li.end();++i){

ri.add(*i);

}

cout<<ri.last4();

char pause;

cin>>pause;

return 0;

}