链表基本操作

#include<stdio.h>
#include<stdlib.h>

struct list
{
    int data;
    struct list *next;
};

//建立链表节点
struct list *create_list()
{
    return calloc(sizeof(struct list),1);
}

//往链表的第n个节点插入新节点
struct list *insert_list(struct list *ls,int n,int data)
{
    struct list *p = ls;
    while(p && n--)
    {
        p = p->next;
    }
    if(NULL == p)
    {
        return NULL;
    }
    struct list *node = create_list();
    node->data = data;
    node->next = p->next;
    p->next = node;
    return node;
}

//删除第n个节点 
int delete_list(struct list *ls,int n)
{
    struct list *p = ls;
    while(p && n--)
    {
        p = p->next;
    }

    if(NULL == p)
    {
        return -1;
    }
    
    struct list *temp = p->next;
    p->next = temp->next;
    free(temp);
    return 0;
}

//删除链表只留头节点
void clear_list(struct list *ls)
{
    struct list *p = ls->next;
    while(p)
    {
        struct list *tmp = p->next;
        free(p);
        p = tmp;
    }
    ls->next = NULL;
}

//判断链表是否为空
int empty_list(struct list *ls)
{
    if(ls->next)
    {
        return 0;
    }
    else
    {
        return -1;
    }
}

//定位第n个节点
struct list *locale_list(struct list *ls,int n)
{
    struct list *p = ls;
    while(p && n--)
    {
        p = p->next;
    }
    if(p == NULL)
    {
        return NULL;
    }
    
    return p;
}

//查找值为data的节点
struct list *elem_list(struct list *ls,int data)
{
    struct list *p = ls;
    while(p)
    {
        if(p->data == data)
            return p;
        p = p->next;
    }
    return NULL;
}

//查找值为data节点的下标
int elem_pos(struct list *ls,int data)
{
    int index = 0;
    struct list *p = ls;
    while(p)
    {
        index++;
        if(p->data == data)
            return index;
        p = p->next;
    }
    return -1;    
}

//统计链表长度
int count_list(struct list *ls)
{
    struct list *p = ls;
    int count = 0;
    while(p)
    {
        count++;
        p = p->next;
    }
    return count;
}

//返回链表最后一个节点
struct list *last_list(struct list *ls)
{
    struct list *p = ls;
    while(p->next)
    {
        p = p->next;
    }
    return p;
}

//合并两个节点
void merge_list(struct list *ls1,struct list *ls2)
{
    last_list(ls1)->next = ls2->next;
}

//遍历打印整个链表
void traverse(struct list *ls)
{
    struct list *p = ls;
    while(p)
    {
        printf("%d\n",p->data);
        p = p->next;
    }
}

int main()
{
    struct list *first = create_list();
    struct list *second = create_list();
    struct list *third = create_list();

    first->next = second;
    second->next = third;
    third->next = NULL;

    first->data = 1;
    second->data = 2;
    third->data = 3;

    insert_list(first,1,10);
    insert_list(first,1,20);
    insert_list(first,1,30);
    delete_list(first,2);

    //clear_list(first);

    traverse(first);
    printf("count = %d\n",count_list(first));

    printf("data = %d\n",locale_list(first,3)->data);
    printf("last data = %d\n",last_list(first)->data);

    struct list *first1 = create_list();
    int i;
    for(i = 0; i < 10; i++)
    {
        insert_list(first1,0,i);
    }        
    merge_list(first,first1);
    traverse(first);
    return 0;
}