Time: 943 ms (12.36%), Space: 18.2 MB (33.96%) - LeetHub

23-merge-k-sorted-lists/23-merge-k-sorted-lists.py

@@ -0,0 +1,47 @@
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
+class Solution:
+    def mergeKLists(self, lists: List[Optional[ListNode]]) -> Optional[ListNode]:
+        
+        # Remove empty lists
+        lists = list(filter(lambda x : False if x == None else True, lists))
+        
+        # Base Case:
+        if len(lists) == 0:
+            return None
+        
+        firstOfAllLists = list(map(lambda x : x.val, lists))
+        rootNode = None
+        currentNode = None
+        
+        while len(lists) > 0:
+            lowestVal = min(firstOfAllLists)
+            indexWithLowest = firstOfAllLists.index(lowestVal)
+            nextNode = ListNode(lowestVal)
+            
+            if currentNode == None:
+                # Initialize nodes (runs once on first iter.)
+                rootNode = nextNode
+                currentNode = nextNode
+            else:
+                # Iterate through nodes
+                currentNode.next = nextNode
+                currentNode = nextNode
+            
+            # Remove lowest value from lists
+            lists[indexWithLowest] = lists[indexWithLowest].next
+
+            # Replace lowest value with next in list
+            if lists[indexWithLowest] == None:
+                lists.pop(indexWithLowest)
+                firstOfAllLists.pop(indexWithLowest)
+            else:
+                firstOfAllLists[indexWithLowest] = lists[indexWithLowest].val
+            
+            
+        return rootNode
+            
+