Remove Duplicates from Sorted List

Problem

Given the head of a sorted linked list, delete all duplicates such that each element appears only once. Return the linked list sorted as well.

Constraints

• The number of nodes in the list is in the range [0, 300].
• -100 <= Node.val <= 100
• The list is guaranteed to be sorted in ascending order.

Solution

The problem Remove Duplicates from Sorted List can be solved by iterating through the list and moving the next pointer for each nodes until no duplicates are found.

Implementation

/**
 * 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 *deleteDuplicates(ListNode *head)
    {
        ListNode *cur = head;
        while (cur && cur->next)
        {
            if (cur->val == cur->next->val)
                cur->next = cur->next->next;
            else
                cur = cur->next;
        }

        return head;
    }
};