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# 1836. Remove Duplicates From an Unsorted Linked List

<https://leetcode.com/problems/remove-duplicates-from-an-unsorted-linked-list>

## Description

Given the `head` of a linked list, find all the values that appear **more than once** in the list and delete the nodes that have any of those values.

Return *the linked list after the deletions.*

**Example 1:**

![](https://assets.leetcode.com/uploads/2021/04/21/tmp-linked-list.jpg)

```

**Input:** head = [1,2,3,2]
**Output:** [1,3]
**Explanation:** 2 appears twice in the linked list, so all 2's should be deleted. After deleting all 2's, we are left with [1,3].
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2021/04/21/tmp-linked-list-1.jpg)

```

**Input:** head = [2,1,1,2]
**Output:** []
**Explanation:** 2 and 1 both appear twice. All the elements should be deleted.
```

**Example 3:**

![](https://assets.leetcode.com/uploads/2021/04/21/tmp-linked-list-2.jpg)

```

**Input:** head = [3,2,2,1,3,2,4]
**Output:** [1,4]
**Explanation:** 3 appears twice and 2 appears three times. After deleting all 3's and 2's, we are left with [1,4].
```

**Constraints:**

* The number of nodes in the list is in the range `[1, 105]`
* `1 <= Node.val <= 105`

## ac

```java
```