[单链表找倒数第k个数] #数据结构

findKthToTail.cpp

typedef struct ListNode{
	int data;
    struct ListNode* next;
}ListNode;
ListNode* findKthToTail(ListNode* pHead,int k){
	ListNode* pFast=pHead,pSlow=pHead;
	if(pHead == null || k<=0 || k> ListLength(pHead))
		return null;
	if(pHead->next == null)
		return pHead;
	for(int i=0;i<k-1;i++){
		pFast = pFast->next;
	}
	while(pFast->next != null){
		pFast = pFast->next;
		pSlow = pSlow->next;
	}
	return pSlow;
}
int ListLength(ListNode* pHead){
	int len = 1;
  	while(pHead->next){
    	len++;
      	pHead = pHead->next;
    }
  	return len;
}