[:solved #224]

Author: ppxyn1

merge-two-sorted-lists/ppxyn1.py

@@ -0,0 +1,31 @@
+# idea : Two Pointer
+# It was first time solving a two-pointer problem using nodes instead of arrays, and I realized I'm still not very familiar with nodes yet.
+class Solution:
+    def mergeTwoLists(self, list1: Optional[ListNode], list2: Optional[ListNode]) -> Optional[ListNode]:
+        dummy = ListNode(None)
+        node = dummy
+        while list1 and list2:
+            if list1.val < list2.val:
+                node.next = list1
+                list1 = list1.next
+            else:
+                node.next = list2
+                list2 = list2.next
+            node = node.next
+        node.next = list1 or list2
+        return dummy.next
+
+
+# Another way to solve it
+# class Solution:
+#     def mergeTwoLists(self, list1: Optional[ListNode], list2: Optional[ListNode]) -> Optional[ListNode]:
+#         if not (list1 and list2):
+#             return list1 or list2
+#         if list1.val < list2.val:
+#             list1.next = self.mergeTwoLists(list1.next, list2)
+#             return list1
+#         else:
+#             list2.next = self.mergeTwoLists(list1, list2.next)
+#             return list2
+
+