题目描述:给定单链表的头指针和一个节点的指针,要在O(1)时间内删除该节点。


链表节点的定义如下:

wKiom1eW0ffgbPKMAAASMFXw4t4167.png

分析:

wKiom1eW0j_CSF5zAAEoB6a00qA747.png

wKioL1eW0mqhDRIbAAAOKHSx9Sw149.png

void DeleteNode(ListNode** pListHead, ListNode* pToBeDeleted)
{
    if(!pListHead || !pToBeDeleted)
        return;

    // 要删除的结点不是尾结点
    if(pToBeDeleted->m_pNext != NULL)
    {
        ListNode* pNext = pToBeDeleted->m_pNext;
        pToBeDeleted->m_nValue = pNext->m_nValue;
        pToBeDeleted->m_pNext = pNext->m_pNext;

        delete pNext;
        pNext = NULL;
    }
    // 链表只有一个结点,删除头结点(也是尾结点)
    else if(*pListHead == pToBeDeleted)
    {
        delete pToBeDeleted;
        pToBeDeleted = NULL;
        *pListHead = NULL;
    }
    // 链表中有多个结点,删除尾结点
    else
    {
        ListNode* pNode = *pListHead;
        while(pNode->m_pNext != pToBeDeleted)
        {
            pNode = pNode->m_pNext;            
        }

        pNode->m_pNext = NULL;
        delete pToBeDeleted;
        pToBeDeleted = NULL;
    }
}

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