finish 83

leetcode/83.py

@@ -0,0 +1,23 @@
+# 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.
+
+# Definition for singly-linked list.
+class ListNode:
+    def __init__(self, val=0, next=None):
+        self.val = val
+        self.next = next
+        
+from typing import Optional
+class Solution:
+    def deleteDuplicates(self, head: Optional[ListNode]) -> Optional[ListNode]:
+        if head is None:
+            return head
+        pointer = head
+        while pointer.next is not None:
+            if pointer.val == pointer.next.val:
+                pointer.next = pointer.next.next
+            else:
+                pointer = pointer.next
+                
+        return head