[리트코드 leetcode] 23. Merge k Sorted Lists (HARD)

leetcode.com/problems/merge-k-sorted-lists/

Merge k Sorted Lists - LeetCode

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# 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[ListNode]) -> ListNode:
        def toNode(lst):
            head = None
            while lst:
                head = ListNode(lst.pop(),head)
            return head
        
        def toList(head):
            lst = []
            while head:
                lst.append(head.val)
                head = head.next
            return lst
        
        lst= []
        
        for node in lists:
            lst += toList(node)
            
        lst.sort()
        return toNode(lst)