题解 | #删除链表的倒数第n个节点#

/*
 * function ListNode(x){
 *   this.val = x;
 *   this.next = null;
 * }
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @param n int整型 
 * @return ListNode类
 */
function removeNthFromEnd( head ,  n ) {
    let fast = head
    let slow = head
    // fast移动
    for(let i = 0; i < n; i++) {
        fast = fast.next
    }
    // 如果fast为空，表示删除的是头结点
    if(fast === null) {
        return head.next
    }
    while(fast.next) {
        fast = fast.next
        slow = slow.next
    }
    slow.next = slow.next.next
    return head
}
module.exports = {
    removeNthFromEnd : removeNthFromEnd
};