前言

本系列主要整理面试中需要掌握的手撕代码题.This section describes the linked list node from bottom problem.

一、BM8 链表中倒数最后k个结点

（1）定义快慢指针,首先让快指针走k个位置;
（2）How quickly and then let the pointer to move at the same time,When at the end of a pointer to the end,慢指针的位置就是倒数第k个.

function FindKthToTail( pHead , k ) {
    
    // write code here
    var fast = pHead;
    var slow = pHead;
    for(var i=0;i<k;i++){
    
        if(fast==null){
    
            return null
        }
        fast = fast.next;
    }

    while(fast){
    
        fast = fast.next;
        slow = slow.next;
    }
    return slow
}

二、BM9 删除链表的倒数第n个节点

（1）First, use the method to find the need to delete the node,Note is positioning to delete a node before;
（2）To determine whether to delete the first node,如果是,直接返回头节点的next;
（3）如果不是,则将该节点的next的next赋值给next.

function removeNthFromEnd( head , n ) {
    
    // write code here
    var slow = head;
    var fast = head;
    for(var i=0;i<n;i++){
    
        if(fast == null){
    
            return head
        }
        fast = fast.next
    }
    if(fast == null){
    
        return head.next
    }
    while(fast.next!=null){
    
        slow = slow.next;
        fast = fast.next;
    }
    slow.next = slow.next.next
    return head
}