[83] Remove Duplicates from Sorted List

https://leetcode.com/problems/remove-duplicates-from-sorted-list/description/

• algorithms
• Easy (41.26%)
• Source Code: 83.remove-duplicates-from-sorted-list.py
• Total Accepted: 316.6K
• Total Submissions: 748.9K
• Testcase Example: '[1,1,2]'

Given a sorted linked list, delete all duplicates such that each element appear only once.

Example 1:

Input: 1->1->2 Output: 1->2

Example 2:

Input: 1->1->2->3->3 Output: 1->2->3

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        if not head or not head.next: return head
        p, q = head, None

        while p:
            q = p.next
            while q and q.val == p.val:
                q = q.next

            p.next = q
            p = q

        return head