Merge Sort Linked List

Moderate

0/80

Average time to solve is 10m

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38 upvotes

Asked in companies

Problem statement

You are given a Singly Linked List of integers. Sort the Linked List using merge sort.

Merge Sort is a Divide and Conquer algorithm. It divides the input into two halves, calls itself for the two halves, and then merges the two sorted halves. The merge() function is used for merging two halves. The merge(arr, L, M, R) is a key process that assumes that arr[L..M] and arr[M + 1...R] are sorted and merges the two sorted subarrays into one.

Detailed explanation ( Input/output format, Notes, Images )

Input Format:

The first line of input contains a single integer T, representing the number of test cases or queries to be run. 
Then the T test cases follow.

The first line of each test case contains the elements of the singly linked list separated by a single space and terminated by -1. Hence, -1 would never be a list element.

Output Format:

For each test case, print the sorted linked list. The elements of the sorted list should be single-space separated, terminated by -1.

The output of each test case is printed in a separate line.

Note:

You are not required to print the output, it has already been taken care of. Just implement the function.

Constraints :

1 <= T <= 10
1 <= N <= 10^4
-10^9 <= data <= 10^9 and data != -1

Where data is the value associated with the node.

Time Limit: 1 sec

Sample Input 1:

Sample Output 1:

-2 1 3 -1
9 9 -1
4 -1

Explanation For Sample Output 1:

For every test case, the sorted list is printed, terminated by -1.

Sample Input 2:

2
1 1 1 -1
3 -3 -1

Sample Output 2:

1 1 1 -1
-3 3 -1

Console