单链表的实现（课本上的算法）

　　大牛无视，小白代码。。。又是无聊的上机课......

#include <iostream>
#include <cstdio>
#include <cstdlib>

using namespace std;

typedef struct node
{
    int data;
    struct node * next;
}node, *linklist;
//顺序建立链表
linklist creat(linklist &l , int n)
{
    l = (linklist)malloc(sizeof(node));
    linklist p, tail;
    tail = l;
    for(int i = 1; i <= n; i++)
    {
        p = (linklist)malloc(sizeof(node));
        cin >> p->data;
        p->next = NULL;
        tail->next = p;
        tail = p;
    }
    return l;
}
//逆序建立链表 算法2.10
void creat_l(linklist &l, int n)
{
    l = (linklist)malloc(sizeof(node));
    l->next = NULL;
    linklist p;
    for(int i = 1; i <= n; i++)
    {
        p = (linklist)malloc(sizeof(node));
        cin >> p->data;
        p->next = l->next; l->next = p;
    }
}

//get i-th elem

int getelem(linklist l, int i)
{
    linklist p;
    p = l->next;
    int j = 1;
    while(p && j < i)
    {
        p = p->next;
        ++j;
    }
    if(!p || j > i)    return 0;
    int e = p->data;
    return e;
}
// 插入 算法2.8
void insert(linklist &l, int i, int e)
{
    linklist p = l;
    int j = 0;
    while(p && j < i-1)
    {
        p = p->next;
        ++j;
    }
    if(!p || j > i-1)
        return;
    linklist s;
    s = (linklist)malloc(sizeof(node));
    s->data = e;
    s->next = p->next;
    p->next = s;
    delete(s);
}
//delete 算法2.9
int del(linklist &l, int i)
{
    linklist p = l;
    int j = 0;
    while(p->next && j < i-1)
    {
        p = p->next; j++;
    }
    if(!(p->next) || j > i-1)    return 0;
    linklist q;
    q = p->next;
    int e = q->data;
    p->next = q->next;
    delete q;
    return e;
}
//合并 算法2.11
void merge(linklist &la, linklist &lb, linklist & lc)
{
    linklist pa = la->next, pb = lb->next, pc;
    lc = pc = la;
    while(pa && pb)
    {
        if(pa ->data < pb->data)
        {
            pc->next = pa;
            pc = pa;
            pa = pa->next;
        }
        else
        {
            pc->next = pb;
            pc = pb;
            pb = pb->next;
        }
    }
    pc->next = pa ? pa : pb;
}
//输出
void print(linklist l)
{
    linklist p = l->next;
    while(p)
    {
        cout << p->data << ' ';
        p = p->next;
    }
    cout << endl;
}

int main()
{
    int n;
    linklist l;
    cout << "Creat a LinkList !" << endl;
    cout << "Please input the length of the LinkList: " << endl;
    cin >> n;
    cout << "Pleast input the elem :" << endl;
    creat(l, n);
    int i;
    print(l);
    cout << "Please input the i-th number you want to get:" << endl;
    cin >> i;
    cout << getelem(l, i) << endl;
    cout << "Please input the number you want to insert and the posion: " << endl;
    int e;
    cin >> i >> e;
    insert(l, i, e);
    print(l);
    cout << "Pleast input the i-th number you want to delete(0 mains not find the number): " << endl;

    int j;
    cin >> j;
    cout << del(l, j) << endl;
    print(l);
    linklist lb, lc;
    cout << "Creat another linklist:" << endl;
    cin >> n;
    creat_l(lb, n);
    print(lb);
    merge(l, lb, lc);
    print(lc);
    return 0;
}