leetcode: 83. Remove Duplicates from Sorted List

# Given a sorted linked list, delete all duplicates such that each element appear only once.
#
# For example,
# Given 1->1->2, return 1->2.
# Given 1->1->2->3->3, return 1->2->3.

class ListNode():
    def __init__(self, x):
        self.val = x
        self.next = None

class Solution():
    def deleteDuplicates(self, head):
        cur = head
        while cur:
            while cur.next and cur.next.val == cur.val:
                cur.next = cur.next.next
            cur = cur.next
        return head


if __name__ == "__main__":
    head, head.next, head.next.next, head.next.next.next, head.next.next.next.next \
        = ListNode(1), ListNode(1), ListNode(2), ListNode(3), ListNode(3)
    assert Solution().deleteDuplicates(head).val == 1