Merge K Sorted Lists
Explore how to combine multiple sorted linked lists into a single sorted list by using the k-way merge technique. Understand the problem constraints, practice your solution in a coding environment, and develop an efficient approach to this common coding interview challenge.
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Statement
You are given an array, lists, containing k singly linked lists. Each of these linked lists is individually sorted in ascending order.
Your task is to merge all k linked lists into a single sorted linked list in ascending order and return the merged list.
Constraints:
klists.lengthklists[i].lengthlists[i][j]Each
lists[i]is sorted in ascending order.The sum of all
lists[i].lengthwill not exceed.
Examples
Understand the problem
Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:
Merge K Sorted Lists
What is the output if the following array is given as input?
lists = [
1 → 2 → 3 → NULL,
12 → 56 → 200 → NULL,
-10 → -2 → 5 → NULL
]
1 → 2 → 3 → 12 → 56 → 200 → -10 → -2 → 5 → NULL
1 → 2 → 3 → -10 → -2 → 5 → 12 → 56 → 200 → NULL
-10 → -2 → 1 → 2 → 3 → 5 → 12 → 56 → 200 → NULL
-10 → -2 → 5 → 1 → 2 → 3 → 12 → 56 → 200 → NULL
Figure it out!
We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.
Try it yourself
Implement your solution in the following coding playground.
# Definition for a Linked List node# class ListNode:# def __init__(self, val=0, next=None):# self.val = val# self.next = nextfrom ds_v1.LinkedList.LinkedList import ListNodedef merge_k_lists(lists):# Replace this placeholder return statement with your codereturn lists[0]