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