[Solved] You are given an array of k linked-lists lists, each linked-list is sorted in ascending order. Merge all the linked-lists into one sorted linked-list and return it.

Question

You are given an array of k linked-lists lists, each linked-list is sorted in ascending order.

Merge all the linked-lists into one sorted linked-list and return it.

Example 1:

Input: lists = [[1,4,5],[1,3,4],[2,6]]
Output: [1,1,2,3,4,4,5,6]
Explanation: The linked-lists are:
[
  1->4->5,
  1->3->4,
  2->6
]
merging them into one sorted list:
1->1->2->3->4->4->5->6

Example 2:

Input: lists = []
Output: []

Example 3:

Input: lists = [[]]
Output: []

Constraints:

  • k == lists.length
  • 0 <= k <= 104
  • 0 <= lists[i].length <= 500
  • -104 <= lists[i][j] <= 104
  • lists[i] is sorted in ascending order.
  • The sum of lists[i].length will not exceed 104.

Python Solution

from heapq import heappop,heappush,heapify

class Solution:
    def mergeKLists(self, lists: List[ListNode]) -> ListNode:
        h = []
        
        for l in lists:
            while l:
                heappush(h,l.val)
                l = l.next
        
        head = ListNode(0)
        head1 = head
        
        while h:
            head.next = ListNode(heappop(h))
            head = head.next
        
        return head1.next
Abhishek Sharma
Abhishek Sharma

Started my Data Science journey in my 2nd year of college and since then continuously into it because of the magical powers of ML and continuously doing projects in almost every domain of AI like ML, DL, CV, NLP.

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