[chapse57] Week 4

merge-two-sorted-lists/chapse57.py

@@ -0,0 +1,28 @@
+# 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 mergeTwoLists(self, list1, list2):
+        """
+        :type list1: Optional[ListNode]
+        :type list2: Optional[ListNode]
+        :rtype: Optional[ListNode]
+        """
+        dummy = ListNode()
+        tail = dummy
+
+
+        while list1 and list2:
+            if list1.val <= list2.val:
+                tail.next = list1
+                list1 = list1.next      
+            else:
+                tail.next = list2
+                list2 = list2.next      
+
+            tail = tail.next
+        tail.next = list1 if list1 else list2 
+
+        return dummy.next