[数据结构与算法]C语言双向链表的实现

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

struct dblnode
{
    int num;
    struct dblnode * prior, * next;
};
typedef struct dblnode Dblnode;
typedef Dblnode * Dblink;

enum result_val{RET_OK = 1000,RET_NO};

int is_malloc_ok( Dblink new_node)
{
    if(new_node == NULL)
    {
        return RET_NO;
    }
    else
    {
        return RET_OK;
    }
}

int create_node( Dblink * new_node)
{
    *new_node = ( Dblink)malloc((unsigned)sizeof(Dblnode));
    if(RET_NO == is_malloc_ok(*new_node))
    {
        return RET_NO;
    }
    else
    {
        return RET_OK;
    }
}

void create_link( Dblink * head)
{
    create_node(head);
	(*head)->prior = *head;
    (*head)->next = *head;
}

void display_link( Dblink head)
{
    Dblink p =NULL;


    if(head == NULL)
    {
        printf("no link !\n");
    }
    else
    {
        p = head->next;

        if(head->next == head)
        {
            printf("the link is empty !\n");
            return;
        }
        else
        {
            while(p != head)
            {
                printf("%d\n",p->num);
                p = p->next;
            }
        }
    }
    
    
}

void insert_node_head( Dblink head, Dblink new_node)
{
    new_node->next = head->next;
    new_node->prior = head;
    head->next = new_node; 
    head->prior = new_node;
}

void insert_node_mind_sort( Dblink  head, Dblink new_node)
{
    Dblink p = NULL;
    Dblink q = NULL;
    p = (head)->next;
    q = head;
    while(p != head && p->num < new_node->num)
    {
        q = p;
        p = p->next;
    }
    
    new_node->next = p;
    new_node->prior =q;
    q->next = new_node;
    new_node->next->prior = new_node;
    

}

void insert_node_tail( Dblink head, Dblink new_node)
{
    new_node->next = head;
    new_node->prior = head->prior;
    head->prior->next =new_node;
    head->prior = new_node;
    
}

void insert_node_mind_front( Dblink head, Dblink new_node,int loc)
{
    Dblink p = NULL;

    p = head->next;
    
    while(p != head && p->num != loc)
    {
        p = p->next;
    }

    new_node->next = p;
    new_node->prior =p->prior;
    p->prior->next = new_node;
    new_node->next->prior = new_node;
}

void insert_node_mind_behand(Dblink head,Dblink new_node,int loc)
{
     Dblink p = NULL;

    p = head->next;
    
    while(p != head && p->num != loc)
    {
        p = p->next;
    }

    new_node->next = p->next;
    new_node->prior =p;
    p->next = new_node;
    new_node->next->prior = new_node;
    
}

void delete_node( Dblink  head,int num)
{
    Dblink p = NULL;
    
    p = head->next;

    while(p != head && p->num != num)
    {
        p = p->next;
    }

     if(p == head)
    {
        printf("NO find\n");  
    }
    else
    {
        p->prior->next = p->next;
        p->next->prior = p->prior;
        
        free(p);
    }
        
    
        
}

int length_link( Dblink head)
{
    Dblink p = NULL;
    int count = 0;
    p = head->next;

    while(p != head)
    {
        count++;
        p = p->next;
    }

    return count;

}

Dblink find( Dblink head,int num)
{
    Dblink p = NULL;
    p = head->next;
    while(p != head && p->num != num)
    {
        p = p->next;
    }
    if(p == head)
    {
        return NULL;
    }
    else
    {
        return p;
    }
}

void make_empty( Dblink head)
{
    Dblink p =NULL;

    p = head->next;
    while(head->next != head)
    {
        p = head->next;
        head->next = head->next->next;
        free(p);
    }

}

void release_link( Dblink * head)
{
    make_empty(*head);

    while(*head != NULL)
    {
        if((*head)->next == *head)
        {
            free(*head);
            
        }
        *head = NULL;
    }
    
    
    
}


int main()
{
    Dblink head = NULL;
    Dblink new_node = NULL;
    Dblink p = NULL;
    int i;
    int loc;
    int num;
    int count=0;

    srand((unsigned)time(NULL));
    create_link(&head);

    for(i = 0; i < 10; i++)
    {
        if(RET_OK == create_node(&new_node))
        {
            new_node->num = rand() % 100;
            //new_node->num = i+1;
            insert_node_mind_sort(head,new_node);
            //insert_node_head(head,new_node);
           // insert_node_tail(head,new_node);
            
        }
        else
        {
            i--;
        }
    }

    display_link(head);

    
    /*count = length_link(head);//长度
    printf("the length is %d\n",count);

    display_link(head);*/

    /*printf("please input the num\n");//查找
    scanf("%d",&num);
    p = find(head,num);
    
    if(p == NULL)
    {
        printf("no found\n");
    }
    else
    {
       printf("the result is %d\n",p->num); 
    }*/
    
    
    printf("\nplease input the num\n");//删除
    scanf("%d",&num);
    
    printf("\nthe result is \n");
    delete_node(head,num);

    display_link(head);
    
    /*if(RET_OK == create_node(&new_node))//插入
    {
        printf("please input the loc\n");
        scanf("%d",&loc);
        printf("please input the num\n");
        scanf("%d",&new_node->num);
        printf("\n");

        //insert_node_mind_front(head,new_node,loc);
        insert_node_mind_behand(head,new_node,loc);

        display_link(head);    
    }*/

    make_empty(head);
    display_link(head);
    release_link(&head);
    display_link(head);

}