数据结构与算法篇 之循环单链表与双链表

链表的基础操作，增删查插 感觉最重要的画出来，一步一步的分析，不要凭空想象，不要凭空想象，不要凭空想象

循环单链表：

#include 
#include 
#define bool int
#define false 0
#define true 1

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

list * init_list()
{
    struct list* head = (list*)malloc(sizeof(list));
    head->next = head;
    head->data = -1;
    return head;
}

list * new_node(int data)
{
    struct list* head = (list*)malloc(sizeof(list));
    head->next = NULL;
    head->data = data;
    return head;
}

int get_list_len(list *head)
{
    if(head == NULL ) return 0;
    int len = 0;
    list *p = head;
    list *tmp = head->next;
    while(tmp->next)
    {
        len++;
        tmp = tmp->next;
        if(p == tmp)
            break;
    }
    return len;
}

bool add_tail(list * head,list * p)
{
    if(head == NULL || p == NULL)
    {
        printf("list or new node is null \n");
        return false;
    }
    int len = get_list_len(head);
    list *tmp = head;
    while(len--)
    {
        tmp = tmp->next;
    }
    p->next = head;
    tmp->next = p;

    return true;
}


bool add_head(list *head,list *p)
{
    if(head == NULL || p == NULL)
    {
        printf("list or new node is null\n");
        return false;
    }
    list *tmp = head;

    p->next = tmp->next;
    tmp->next = p;

    return true;
}

bool search_node(list *head,int data,bool flag)
{
    if(head == NULL) return false;

    list *p = head->next;
    list *tmp = head;
    while(1)
    {
        if(data == p->data)
        {
            printf("%d is in the list\n",data);
            if(flag == true)
            {
                 tmp->next = p->next;
                 p->next = NULL;
                 free(p);
            }
            break;
        }
        if(p->next == head)
        {
            printf("%d is not in the list\n",data);
            break;
        }
        tmp = p;
        p = p->next;
    }

}

bool delete_tail_node(list *head)
{
    if (head == NULL) return false;
    int i = get_list_len(head) - 1;
    struct list *p = head;

    while(i--)
    {
        p = p->next;
    }
    p->next->next = NULL;
    p->next = head;

    free(p->next);
}

bool delete_head_node(list *head)
{
    if(head == NULL) return false;

    struct list *p = head;
    struct list *tmp = p->next;
    tmp = p->next ;
    p->next = p->next->next;
    tmp->next = NULL;
    free(tmp);

}

bool delete_appoint_node(list *head,int num)
{
    if(head == NULL) return false;
    int len = 0;
    if(len = get_list_len(head) < num) return false;

    struct list *p = head->next;
    struct list *tmp = head;
    num--;
    while((--len) && (--num))
    {
        p = p->next;
    }
    tmp = p->next;
    p->next = p->next->next;
    tmp->next = NULL;

    free(tmp);
}

bool insert_tail_or_head(list *head,unsigned int num,list *new,bool flag)
{
    if (head == NULL || new == NULL)
    {
        printf("head or new is null");
        return false;
    }
    if(get_list_len(head) < num) return false;

    struct list *p = head;
    if(flag == true)
    {
        while(num--)
        {
            p = p->next;
        }
    }
    else
    {
        while(--num)
        {
            p = p->next;
        }
    }
    new->next = p->next;
    p->next = new;

    return true;
}

bool show_list(list* head)
{
    if(head == NULL) return false;
    struct list *p = head->next;
    int i = get_list_len(head);
    for ( ;i > 0;p = p->next,--i)
    {
        printf("%d",p->data);
        printf("-->");
    }

    printf("\n");
    return true;
}

int main()
{
    struct list* head = init_list();
    int i = 0;
    for (;i < 10;i++)
    {
        add_tail(head,new_node(i));
    }
    printf("start...\n");
    show_list(head);
    printf("end...\n");

    int len = get_list_len(head);
    printf("list len %d\n",len);

    delete_tail_node(head);
    show_list(head);

    delete_head_node(head);
    show_list(head);

    delete_appoint_node(head,2);
    show_list(head);

    len = get_list_len(head);
    printf("list len %d\n",len);

    insert_tail_or_head(head,2,new_node(23),true);
    show_list(head);
    search_node(head,2,true);
    show_list(head);
    return 1;
}

循环双链表：

#include 
#include 
#define bool int
#define false 0
#define true 1

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

list * init_list()
{
    struct list* head = (list*)malloc(sizeof(list));
    head->next = head;
    head->prev = head;
    head->data = -1;
    return head;
}

list * new_node(int data)
{
    struct list* head = (list*)malloc(sizeof(list));
    head->next = NULL;
    head->prev = NULL;
    head->data = data;
    return head;
}

int get_list_len(list *head)
{
    if(head == NULL) return 0;
    int len = 0;
    list *p = head;
    list *tmp = head->next;
    while(tmp->next)
    {
        len++;
        tmp = tmp->next;
        if(p == tmp)
            break;
    }
    return len;
}

bool add_tail(list * head,list * p)
{
    if(head == NULL || p == NULL)
    {
        printf("list or new node is null \n");
        return false;
    }
    int len = get_list_len(head);
    list *tmp = head;
    while(len--)
    {
        tmp = tmp->next;
    }
    p->next = head;
    p->prev = tmp;
    head->prev = p;
    tmp->next = p;
    return true;
}


bool add_head(list *head,list *p)
{
    if(head == NULL || p == NULL)
    {
        printf("list or new node is null\n");
        return false;
    }
    list *tmp = head;

    p->next = tmp->next;
    p->prev = tmp;
    tmp->next->prev = p;
    tmp->next = p;

    return true;
}

bool search_node(list *head,int data,bool flag)
{
    if(head == NULL) return false;

    list *p = head->next;
    while(1)
    {
        if(data == p->data)
        {
            printf("%d is in the list\n",data);
            if(flag == true)
            {
                 p->next->prev = p->prev;
                 p->prev->next = p->next;

                 p->next = NULL;
                 p->prev = NULL;
                 free(p);
            }
            break;
        }
        if(p->next == head)
        {
            printf("%d is not in the list\n",data);
            break;
        }
        p = p->next;
    }

}

bool delete_tail_node(list *head)
{
    if (head == NULL) return false;

    struct list *p = head;
    int i = get_list_len(head) - 1;
    while(i--)
    {
        p = p->next;
    }
    p->next->prev = p->prev;
    p->prev->next = p->next;
    p->prev = NULL;
    p->next = NULL;
    free(p);
}

bool delete_head_node(list *head)
{
    if(head == NULL) return false;

    struct list *p = head;
    struct list *tmp = head->next;
    p->next->next->prev = p;
    p->next = p->next->next;
    tmp->next = NULL;
    tmp->prev = NULL;
    free(tmp);

}

bool delete_appoint_node(list *head,int num)
{
    if(head == NULL) return false;

    if(get_list_len(head) < num) return false;

    struct list *p = head->next;
    struct list *tmp = head;
    while( --num)
    {
        p = p->next;
    }
    p->next->prev = p->prev;
    p->prev->next = p->next;

    p->next = NULL;
    p->prev = NULL;
    free(p);
}

bool insert_tail_or_head(list *head,unsigned int num,list *new,bool flag)
{
    if (head == NULL || new == NULL)
    {
        printf("head or new is null");
        return false;
    }
    if(get_list_len(head) < num) return false;

    struct list *p = head;
    if(flag == true)
    {
        while(num--) p = p->next;
    }
    else
    {
        while(--num) p = p->next;
    }
    new->next = p->next;
    new->prev = p;
    p->next->prev = new;
    p->next = new;

    return true;
}

bool show_list(list* head)
{
    if(head == NULL) return false;
    struct list *p = head->next;
    int data;

    for ( ;p->next != head;p = p->next)
    {
        printf("%d",p->data);
        printf("-->");
    }
    printf("%d",p->data);

    printf("\n");
    return true;
}

int main()
{
    struct list* head = init_list();
    int i = 0;
    for (;i < 10;i++)
    {
        add_tail(head,new_node(i));
    }
    printf("start...\n");
    show_list(head);
    printf("end...\n");

    int len = get_list_len(head);
    printf("list len %d\n",len);

    delete_tail_node(head);
    delete_head_node(head);
    delete_head_node(head);

    show_list(head);
    delete_appoint_node(head,2);
    show_list(head);

    len = get_list_len(head);
    printf("list len %d\n",len);

    insert_tail_or_head(head,2,new_node(23),false);
    show_list(head);
    search_node(head,2,true);
    show_list(head);
    return 1;
}