466. Remove Duplicates From an Unsorted Linked List

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:

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:

Input: head = [2,1,1,2]

Output: []

Explanation: 2 and 1 both appear twice. All the elements should be deleted.

Now Your Turn!

Pick the correct output for the given input

Consider the linked list [5,6,5,7,8,6,9]. What will be the resulting list after removing duplicates?

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Let’s go through a few more examples, step by step, to make it clearer.

Constraints:

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

Hints

Frequently Occurring Doubts

Interview Follow-up Questions

0
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode() : val(0), next(nullptr) {}
* ListNode(int x) : val(x), next(nullptr) {}
* ListNode(int x, ListNode *next) : val(x), next(next) {}
* };
*/
class Solution {
public:
ListNode* deleteDuplicatesUnsorted(ListNode* head) {
// Your code goes here
}
};
Test Case

Input:

Head
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