使用js删除链表中的重复项

function ListNode(val) {
  this.val = val;
  this.next = null;
}

function deleteDuplicates(head) {
  if (!head || !head.next) {
    return head;
  }
  
  let hash = {};
  let curr = head;
  let prev = null;
  
  while (curr) {
    if (hash[curr.val]) {
      prev.next = curr.next;
    } else {
      hash[curr.val] = true;
      prev = curr;
    }
    curr = curr.next;
  }
  
  return head;
}

// 示例用法
let head = new ListNode(1);
head.next = new ListNode(2);
head.next.next = new ListNode(2);
head.next.next.next = new ListNode(3);

let result = deleteDuplicates(head);
console.log(result); // 输出: ListNode { val: 1, next: ListNode { val: 2, next: ListNode { val: 3, next: null } } }