leetcode 707设计链表-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_55566416/article/details/123227485

这篇博客介绍了如何使用C语言实现链表数据结构，包括创建链表、按索引获取元素、在头部、尾部及中间插入元素以及按索引删除元素的操作。这些基本操作对于理解和掌握链表至关重要。

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typedef struct myListNode
{
    int elem;                   //数据域
    struct myListNode* next;    //指针域
}myListNode;


typedef struct MyLinkedListTag
{
    int    val;
    int    count;
    struct myListNode* head;

} MyLinkedList;


MyLinkedList* myLinkedListCreate()
{
    MyLinkedList* myLink = malloc(sizeof(MyLinkedList));
    myLink->head  = NULL;
    myLink->count = 0;
    return myLink;
}

int myLinkedListGet(MyLinkedList* obj, int index)
{
    if(obj->count<index)
    return -1;
    myListNode*indexit=obj->head;
    int count=0;
    int value=-1;
    while(indexit!=NULL)
    {
        if(count==index)
        {
            value=indexit->elem;
            break;
        }
        indexit=indexit->next;
        count++;
    }
    return value;
}

void myLinkedListAddAtHead(MyLinkedList* obj, int val)
{
   myListNode*newnode=(myListNode*)malloc(sizeof(myListNode));
    newnode->elem=val;
    newnode->next=NULL;
    if(obj->head==NULL)
    {
        obj->head=newnode;
        obj->count++;
    }
    else
    {
        newnode->next=obj->head;
        obj->head=newnode;
        obj->count++;
    }
}

void myLinkedListAddAtTail(MyLinkedList* obj, int val)
{
    myListNode*newnode=(myListNode*)malloc(sizeof(myListNode));
    newnode->elem=val;
    newnode->next=NULL;
    if(obj->head==NULL)
    {
        obj->head=newnode;
        obj->count++;
    }
    else
    {
        myListNode*temp=obj->head;
        while(temp->next!=NULL)
        {
            temp=temp->next;
        }
        temp->next=newnode;
        newnode->next=NULL;
        obj->count++;
    }
}

void myLinkedListAddAtMiddle(struct myListNode* nodeIt, int val)
{
    myListNode*newnode=(myListNode*)malloc(sizeof(myListNode));
    newnode->elem=val;
    newnode->next=NULL;
    newnode->next=nodeIt->next;
    nodeIt->next=newnode;
}



void myLinkedListAddAtIndex(MyLinkedList* obj, int index, int val)
{
    if(obj->count<index)
    return ;
    if(index<=0)
    {
        myLinkedListAddAtHead(obj,val);
        return;
    }
    myListNode*pointpre=obj->head;
    myListNode*point=obj->head;
    int count=0;
    while(point!=NULL)
    {
        if(count>=index)
        {
            break;
        }
        count++;
        pointpre=point;
        point=point->next;
    }
    if(count==0)
    {
        myLinkedListAddAtHead(obj,val);
    }
    else if(count==obj->count)
    {
        myLinkedListAddAtTail(obj,val);
    }
    else{
        myLinkedListAddAtMiddle(pointpre,val);
        obj->count++;
    }
}

void myLinkedListDeleteAtIndex(MyLinkedList* obj, int index)
{
   if(obj->count<=index)
   {
       return;
   }
    myListNode*pointpre=obj->head;
    myListNode*point=obj->head;
    int count=0;
    while(point!=NULL)
    {
        if(count==index)
        break;
        pointpre=point;
        point=point->next;
        count++;
    }
    if(count==0)
    {
        obj->head=obj->head->next;
    }
    else{
        pointpre->next=point->next;
    }
    free(point);
    obj->count--;
    if(obj->count==0)
    {
        obj->head=NULL;
    }

}

void myLinkedListFree(MyLinkedList* obj)
{
    myListNode*pointpre=obj->head;
    myListNode*point=obj->head;
    while(point!=NULL)
    {
        point=point->next;
        free(pointpre);
        pointpre=point;
    }
    free(obj);
}