Create maximum-twin-sum-of-a-linked-list.py

Author: kamyu104

Python/maximum-twin-sum-of-a-linked-list.py

@@ -0,0 +1,32 @@
+# Time:  O(n)
+# Space: O(1)
+
+# Definition for singly-linked list.
+class ListNode(object):
+    def __init__(self, val=0, next=None):
+        self.val = val
+        self.next = next
+
+
+class Solution(object):
+    def pairSum(self, head):
+        """
+        :type head: Optional[ListNode]
+        :rtype: int
+        """
+        def reverseList(head):
+            dummy = ListNode()
+            while head:
+                dummy.next, head.next, head = head, dummy.next, head.next
+            return dummy.next
+
+        dummy = ListNode(next=head)
+        slow = fast = dummy
+        while fast.next and fast.next.next:
+            slow, fast = slow.next, fast.next.next
+        result = 0
+        head2 = reverseList(slow)
+        while head:
+            result = max(result, head.val+head2.val)
+            head, head2 = head.next, head2.next
+        return result