leetcode刷题记录——19删除链表的倒数第N个节点

题目：leetcode刷题记录——19删除链表的倒数第N个节点

代码：

var removeNthFromEnd = function(head, n) {
    let dummyNode = new ListNode(0);
    dummyNode.next = head;

    let firstNode = dummyNode;
    let lastNode = dummyNode;
    let i = 0;
    while(lastNode !== null) {
        lastNode = lastNode.next;
        if (i > n) {
            firstNode = firstNode.next;
        }
        i++;
    }
    
    firstNode.next = firstNode.next.next;

    return dummyNode.next;
};