我正在尝试从链接列表中删除重复项，但是重复项仍然存在

Question

我有以下类 ListNode

class ListNode {
    constructor(val) {
        this.val = val
        this.next = null
    }
}

我试图通过将值存储在哈希中来删除重复值，如果存在这些值，则不应使用这些值形成新节点；但是，我所完成的只是当前列表的副本。我不确定我在哈希中做错了什么。我的逻辑结构不正确吗？

const deleteDuplicates = (head) => {
    let newNode = new ListNode('dummy')
    let current = newNode
    let headHash = {}

    while (head) {
        if (headHash[head.val] === undefined) {
            if (newNode.next === null) newNode.next = new ListNode(head.val)
            else {
                newNode = newNode.next
                newNode.next = new ListNode(head.val)
            }
        }
        headHash = (headHash[head.val] || 0) + 1
        console.log(headHash, head.val);
        head = head.next

    }
    return current.next
}

const l = new ListNode(1)
l.next = new ListNode(1)
l.next.next = new ListNode(2)

const l2 = new ListNode(1)
l2.next = new ListNode(1)
l2.next.next = new ListNode(2)
l2.next.next.next = new ListNode(3)
l2.next.next.next.next = new ListNode(3)


console.log(deleteDuplicates(l));
console.log(deleteDuplicates(l2));

Answer 1

违规行似乎是这一行：

headHash = (headHash[head.val] || 0) + 1

您必须将headHash 的当前头值属性分配给一个未定义的值，而不是将整个headHash 分配给一个值。请看下面的代码：

class ListNode {
  constructor(val) {
    this.val = val;
    this.next = null;
  }
}
const deleteDuplicates = (head) => {
  let newNode = new ListNode("dummy");
  let current = newNode;
  let headHash = {};

  while (head) {
    if (headHash[head.val] === undefined) {
      if (newNode.next === null) {
          newNode.next = new ListNode(head.val);
      } else {
          newNode = newNode.next;
          newNode.next = new ListNode(head.val);
        }
    }
    // headHash = (headHash[head.val] || 0) + 1 // <- offending line
    headHash[head.val] = (headHash[head.val] || 0) + 1; // You need to assign the value to the headHash's key, not to the headHasn itself.
    head = head.next;
  }
  return current.next;
};

const l = new ListNode(1);
l.next = new ListNode(1);
l.next.next = new ListNode(2);

const l2 = new ListNode(1);
l2.next = new ListNode(1);
l2.next.next = new ListNode(2);
l2.next.next.next = new ListNode(3);
l2.next.next.next.next = new ListNode(3);



console.log(deleteDuplicates(l));
console.log(deleteDuplicates(l2));