剑指offer——倒数第k个节点

Posted 2022-02-05 wangyufeiaichiyu

先走k-1步，然后判断fast有没有到空为止.

/*
public class ListNode 
    int val;
    ListNode next = null;

    ListNode(int val) 
        this.val = val;
    
*/
public class Solution 
    public ListNode FindKthToTail(ListNode head,int k) 
        
        if(head==null||k<=0)
        
            return null;
        
        
        ListNode fast=head;
        ListNode slow=head;
        
        for(int i=1;i<k;i++)
        
            if(fast.next!=null)
            
                fast=fast.next;
            
            else
            
                return null;
            
        
        
        while(fast.next!=null)
        
            fast=fast.next;
            slow=slow.next;
        
        return slow;