单链表的基本操作

#include <iostream>
#include<bits/stdc++.h>
using namespace std;
class List;
struct LinkNode
{
    int data;
    LinkNode *link;
    LinkNode(LinkNode* ptr=NULL)
    {
        link=ptr;
    }
    LinkNode(const int item,LinkNode* ptr=NULL)
    {
        data=item;
        link=ptr;
    }
};
class List
{
public:
    List()
    {
        first=new LinkNode;
    }
    void input();
    void output();
    friend void Union(List &a,List &b);

    int Length()const;
    int Search(int x);
    LinkNode *Locate(int i);
    int getData(int i);
    bool Insert(int i,int &x);
    bool Remove(int i,int &x);
    LinkNode* Sort(LinkNode* first);


    LinkNode *first;
};
void List::input()
{
    int x,data;
    cin>>x;
    for(int i=0; i<x; ++i)
    {
        cin>>data;
        LinkNode *newNode=new LinkNode(data);
        if(newNode==NULL)
        {
            cerr<<"存储分配失败！"<<endl;
            exit(1);
        }
        newNode->link=first->link;
        first->link=newNode;
    }
}
void List::output()
{
    LinkNode *current=first->link;
    while(current!=NULL)
    {
        cout<<current->data<<endl;
        current=current->link;
    }
}
int List::Length()const//{1,2}A包含2个元素
{
    LinkNode *p=first->link;
    int count=0;
    while(p!=NULL)
    {
        p=p->link;
        count++;
    }
    return count;
}
int List::Search(int x)  //返回2的位置是1，从1开始
{
    int k=1;
    LinkNode *current=first->link;
    while(current!=NULL)
    {
        if(current->data!=x)
        {
            current=current->link;
            k++;
        }
        else
        {
            break;
        }
    }
    if(current!=NULL)
        return k;
    else
        return k=0;
}
LinkNode *List::Locate(int i)//返回第1个的地址
{
    if(i<0)
        return NULL;
    LinkNode *current=first;
    int k=0;
    while(current!=NULL&&k<i)
    {
        current=current->link;
        k++;
    }
    return current;
}
int List::getData(int i)//得到第1个的值--2
{
    int x;
    LinkNode *current =Locate(i);
    x=current->data;
    return x;
}
bool List::Insert(int i,int &x)
{
    LinkNode *current =Locate(i);
    if(current==NULL)
        return false;
    LinkNode *newNode=new LinkNode(x);
    if(newNode==NULL)
    {
        cerr<<"存储分配失败！"<<endl;
        exit(1);
    }
    newNode->link=current->link;
    current->link=newNode;
    return true;
}
bool List::Remove(int i,int &x)
{
    LinkNode *current =Locate(i-1);
    if(current==NULL||current->link==NULL)
        return false;
    LinkNode *del=current->link;
    current->link=del->link;
    x=del->data;
    delete del;
    return true;
}
void Union(List &a,List &b)
{
    int n=a.Length(),m=b.Length(),i,k,x;
    for(i=1; i<=m; ++i)
    {
        x=b.getData(i);
        k=a.Search(x);
        //cout<<k<<endl;
        if(k==0)
        {
            a.Insert(n,x);
            //cout<<a.first->link->data;
            n++;
        }
    }
}
LinkNode* List::Sort(LinkNode* first)
{
    LinkNode* pNode1 = first;
    LinkNode* pNode2 = first;
    if(first == NULL)
        return NULL;
    for(; pNode1->link!=NULL; pNode1=pNode1->link)
    {
        for(pNode2=first; pNode2->link!=NULL; pNode2=pNode2->link)
        {
            if(pNode2->data>pNode2->link->data)
            {
                int temp = pNode2->data;
                pNode2->data = pNode2->link->data;
                pNode2->link->data = temp;
            }
        }
    }
    return first;
}
int main()
{
    List a;
    a.input();
    //a.output();

    List b;
    b.input();
    //b.output();
    //cout<<endl;
    Union(a,b);
    //a.output();
    a.Sort(a.first);
    a.output();
    return 0;
}