1 精要

本质还是 双指针

1.1 所谓的模板

1.2 java语法处理

1.3 more 其他双指针的总结：

来自西加 https://leetcode-solution-leetcode-pp.gitbook.io/leetcode-solution/91/two-pointers

2 code

        public ListNode FindKthToTail (ListNode pHead, int k) {
        if(pHead==null || k<=0 )
			return null;
		int len = GetLen(pHead);
		if(k>len)
			return null;
		
		// write code here
		ListNode fast  = pHead, slow = pHead;
		//move k 
		int step = k;
		while(step!=0){
			
			fast= fast.next;
			step--;
		}
		while(fast!=null){
			
			fast = fast.next;
			slow = slow.next;
		}
		return slow;
    }

	int GetLen(ListNode pH){
		if(pH==null)return 0;
		int l =0;
		while(pH!=null){
		l++;
		pH= pH.next;
		}
		return l;
	}