查找链表中倒数第N个结点

ListNode* findFromEnd(ListNode* list, int n) {
	ListNode* fast = list;
	ListNode* slow = list;
	while(fast && n--) {	//先走N步
		fast = fast->next;
	}
	while(fast) {	//当fast为空时 slow刚好指在目标元素上
		fast = fast->next;
		slow = slow->next;
	}
	return slow;
}