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83. Remove Duplicates from Sorted List (Easy)

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.

 

Example 1:

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

Example 2:

Input: head = [1,1,2,3,3]
Output: [1,2,3]

 

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.

Companies: Amazon, Uber, Google

Related Topics:
Linked List

Similar Questions:

• Remove Duplicates from Sorted List II (Medium)
• Remove Duplicates From an Unsorted Linked List (Medium)

Solution 1.

// OJ: https://leetcode.com/problems/remove-duplicates-from-sorted-list
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        ListNode *p = head;
        while (p) {
            ListNode *q = p->next;
            while (q && q->val == p->val) {
                p->next = q->next;
                delete q;
                q = p->next;
            }
            p = p->next;
        }
        return head;
    }
};