求鏈表中倒數第K個節點

1、求鏈表中倒數第K個節點

[cpp]
ListNode* FindKthToTail(ListNode* pListHead, unsigned int k) 
{ 
        if(pListHead == NULL || k == 0) 
                return NULL; 
  
        ListNode *pAhead = pListHead; 
        ListNode *pBehind = NULL; 
  
        for(unsigned int i = 0; i < k - 1; ++ i) 
        { 
                pAhead = pAhead->m_pNext; 
        if(pAhead == NULL) 
            return NULL; 
        } 
  
        pBehind = pListHead; 
  
        while(pAhead->m_pNext != NULL) 
        { 
                pAhead = pAhead->m_pNext; 
                pBehind = pBehind->m_pNext; 
        } 
  
        return pBehind; 
} 

ListNode* FindKthToTail(ListNode* pListHead, unsigned int k)
{
        if(pListHead == NULL || k == 0)
                return NULL;
 
        ListNode *pAhead = pListHead;
        ListNode *pBehind = NULL;
 
        for(unsigned int i = 0; i < k - 1; ++ i)
        {
                pAhead = pAhead->m_pNext;
  if(pAhead == NULL)
   return NULL;
        }
 
        pBehind = pListHead;
 
        while(pAhead->m_pNext != NULL)
        {
                pAhead = pAhead->m_pNext;
                pBehind = pBehind->m_pNext;
        }
 
        return pBehind;
}

要注意一些錯誤處理機制；