每天一个小算法（4）----在O(1)时间删除指定结点

O(1)时间内删除结点的思路只能是复制该结点下一个结点的数据，然后删除该结点的下一个结点，来等效删除此结点。

需要注意的地方是删除头结点和尾结点的处理。

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
typedef struct Node
{
    int data;
    Node* next;
}Node, *List;

List createList(int num) //随机生成数字，构造链表
{
    List aList = (List)malloc(sizeof(Node));
    aList->next = NULL;
    aList->data = 0;
    Node* qT = aList;

     // srand((int)time(0));
     for ( int i=0; i< num; ++i)
     {
         Node* pTN = (Node*)malloc(sizeof(Node));
         pTN->data = rand()%100;
         pTN->next = NULL;
         qT->next = pTN;
         qT = pTN;
     }
     return aList;
}

void printList(List aList)    //打印链表
{
    if ( aList == NULL || aList->next == NULL )
        return;

    Node* pT = aList->next;
    printf("element of list:
	");
    while( pT != NULL )
    {
        printf("%d ", pT->data);
        pT = pT->next;
    }

    printf("
");
}

void deleteList(List aList)    //删除链表
{}


//删除结点主算法
void deleteNode(List aList, Node* pNode)
{
    if ( aList == NULL || pNode == NULL )
        return;

    if ( aList == pNode )
    {
        printf("refuse to delete head node
");
        return;
    }

    if ( pNode->next == NULL )
    {
        Node* pT = aList->next;
        while ( pT->next != NULL )
        {
            pT = pT->next;
        }

        delete pNode;
        pT->next == NULL;
    }

    Node* pN = pNode->next;
    pNode->data = pNode->next->data;
    pNode->next = pNode->next->next;

    delete pN;
}

int main(int argc, char const *argv[])
{
     srand((int)time(0));
    List aList = createList(5);
    printList(aList);
    deleteNode(aList,aList->next->next);
    printList(aList);
    deleteList(aList);
    
    return 0;
}