C语言 单链表节点的插入和删除_c 单链 链表 删除

用C语言实现单链表的插入和删除，主要用到了“双指针”的方法。

一、有头单链表

1、删除指定节点

void deleteNode_headed(Listnode* head,int deleteData)
{
    Listnode* fast = head->next;
    Listnode* slow = head;
    while(fast != NULL) //遍历链表找到要删除的节点
    {
        if(fast->data == deleteData)//找到了则删除节点
        {
            slow->next = fast->next;
            free(fast);
            fast = NULL;
            head->data--;
            return;
        }
        fast = fast->next;
        slow = slow->next;
    }
    printf("The node is not found.\n");//找不到则打印提示信息
    return;
}

2、插入指定节点

（1）插入到单链表头部

void insertNode_headed_head(Listnode* head, Listnode* nodeAdded)
{
    head->data++;
    nodeAdded->next = head->next;
    head->next = nodeAdded;
}

（2）插入到单链表尾部

void insertNode_headed_tail(Listnode* head, Listnode* nodeAdded)
{
    head->data++;
    while(head->next != NULL)
    {
        head = head->next;
    }
    head->next = nodeAdded;
    nodeAdded->next = NULL;
}

（3）插入到有序单链表，使链表依然有序

void insertNode_headed_ordered(Listnode* head, Listnode* nodeAdded,int(*comp)(const void *, const void *))
{
    Listnode* fast = head->next;
    Listnode* slow = head;
    while(fast != NULL) //寻找比插入节点大的节点
    {
        if(comp(fast,nodeAdded) > 0)    //找到了则插入
        {
            slow->next = nodeAdded;
            nodeAdded->next = fast;
            head->data++;
            return;
        }
        fast = fast->next;
        slow = slow->next;
    }
    slow->next = nodeAdded; //没找到则插入到链表的尾部
    nodeAdded->next = NULL;
    head->data++;
    return;
}

二、无头单链表

1、删除指定节点

Listnode* deleteNode_headless(Listnode* head,int deleteData)
{
    if(head == NULL)    //若为空链表，打印提示信息
    {
        printf("The node is not found.\n");
        return head;
    }
 
    Listnode* slow = head;
    Listnode* fast = head->next;
 
    if(slow->data == deleteData)    //若删除的是第一个节点
    {
        free(slow);
        slow = NULL;
        head = fast;
        return head;
    }
 
    while(fast != NULL) //遍历链表找到要删除的节点
    {
        if(fast->data == deleteData)//找到了则删除节点
        {
 
            slow->next = fast->next;
            free(fast);
            fast = NULL;
            return head;
        }
        fast = fast->next;
        slow = slow->next;
    }
    printf("The node is not found.\n");//找不到则打印提示信息
    return head;    //因为可能会将头节点赋值为NULL（只有一个节点，且需要删除的情况），
}                   //又因为是值传递的头节点，所以要返回头节点

2、插入指定节点

（1）插入到单链表头部

Listnode* insertNode_headless_head(Listnode* head, Listnode* nodeAdded)
{
    nodeAdded->next = head;
    return nodeAdded;
}

（2）插入到单链表尾部

Listnode* insertNode_headless_tail(Listnode* head, Listnode* nodeAdded)
{
    if(head == NULL)    //判断是否是空链表
    {
        nodeAdded->next = NULL;
        return nodeAdded;
    }
    Listnode* temp = head;
    while(temp->next != NULL)
    {
        temp = temp->next;
    }
    temp->next = nodeAdded;
    nodeAdded->next = NULL;
    return head;
}

（3）插入到有序单链表，使链表依然有序

Listnode* insertNode_headless_ordered(Listnode* head, Listnode* nodeAdded,int(*comp)(const void *, const void *))
{
    if(head == NULL)    //判断是否为空链表
    {
        nodeAdded->next = NULL;
        return nodeAdded;
    }
    Listnode* slow = head;
    if(comp(slow,nodeAdded) > 0)    //若插入节点比头节点小，则将插入节点作为头节点
    {
        nodeAdded->next = slow;
        return nodeAdded;
    }
    Listnode* fast = head->next;
    while(fast != NULL) //找到比插入节点大的节点
    {
        if(comp(fast,nodeAdded) > 0)    //如果找到则插入
        {
            slow->next = nodeAdded;
            nodeAdded->next = fast;
            return head;
        }
        fast = fast->next;
        slow = slow->next;
    }
    slow->next = nodeAdded; //否则插入到链表尾部
    nodeAdded->next = NULL;
    return head;
}