Create linked-list-frequency.py

Author: kamyu104

Python/linked-list-frequency.py

@@ -0,0 +1,20 @@
+# Time:  O(n)
+# Space: O(1)
+
+# linked list
+class Solution(object):
+    def frequenciesOfElements(self, head):
+        """
+        :type head: Optional[ListNode]
+        :rtype: Optional[ListNode]
+        """
+        curr = dummy = ListNode(0)
+        cnt = 0
+        while head:
+            cnt += 1
+            if not head.next or head.next.val != head.val:
+                curr.next = ListNode(cnt)
+                curr = curr.next
+                cnt = 0
+            head = head.next
+        return dummy.next