Leetcode: Remove Duplicates from Sorted List

Remove Duplicates from Sorted List | LeetCode OJ

1. Iterate through the list and delete next node if its value matches the current node

2. Delete operation can be simply performed by setting the next pointer to next pointer of next node

Remarks:

1. O(n) time, O(1) space
2. Note how we can avoid adding a separate condition for empty list.

# 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
        """
        p = head
        while p:
            while p.next and p.val == p.next.val:
                p.next = p.next.next
            p = p.next
        return head
    def deleteDuplicates(self, head):
        if not head: return None
        p = head
        while p.next:
            if p.val == p.next.val:
                p.next = p.next.next
            else:
                p = p.next
        return head