> For the complete documentation index, see [llms.txt](https://liuxue2010.gitbook.io/data-structure-and-algorithms/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://liuxue2010.gitbook.io/data-structure-and-algorithms/linked-list/remove-duplicates-from-unsorted-list.md).

# Remove Duplicates from Unsorted List

```
removeDuplicatesOf(node, head)
```

```
    if(node == node.next || node.next == head)
        return
    else if(node.value == node.next.value)
        node.next = node.next.next
        removeDuplicatesOf(node, head)
    else
        removeDuplicatesOf(node.next, head)
```

```
/**
 * 本代码由九章算法编辑提供。版权所有，转发请注明出处。
 * - 九章算法致力于帮助更多中国人找到好的工作，教师团队均来自硅谷和国内的一线大公司在职工程师。
 * - 现有的面试培训课程包括：九章算法班，系统设计班，算法强化班，Java入门与基础算法班，Android 项目实战班，Big Data 项目实战班，
 * - 更多详情请见官方网站：http://www.jiuzhang.com/?source=code
 */

/**
 * Definition for ListNode
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    /**
     * @param head: The first node of linked list.
     * @return: head node
     */
    public ListNode removeDuplicates(ListNode head) { 
        HashSet<Integer> hash = new HashSet<Integer>();

        ListNode dummy = new ListNode(0);
        dummy.next = head;
        head = dummy;
        while (head.next != null) {
            if (hash.contains(head.next.val)) {
                head.next = head.next.next;
            } else {
                hash.add(head.next.val);
                head = head.next;
            }
        }

        return dummy.next;
    }  
}
```