Reverse Linked List

Easy

0/40

Average time to solve is 15m

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183 upvotes

Asked in companies

Problem statement

You are given a Singly Linked List of integers. You need to reverse the Linked List by changing the links between nodes.

Example:

Input:
2 4 5 -1

Output:
5 4 2 -1

Explanation: 2->4->5 is the initial linked list. If we reverse this, we get 5->4->2.

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

Input Format :

The first line 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 :

Print the reversed linked list. The elements of the reversed list should be single-space separated, terminated by -1.

Note :

You do not need to print anything, just return the head of the reversed linked list.

Sample Input 1 :

1 2 4 -1

Sample Output 1 :

4 2 1 -1

Explanation for Sample Input 1 :

1->2->4 is the initial linked list. If we reverse this, we get 4->2->1.

Sample Input 2 :

1
1 1 1 -1

Sample Output 2 :

1 1 1 -1

Constraints :

1 <= 'N' <= 10^4
0 <= 'data' <= 10^9

Where 'N' is the number of nodes in the linked list.

Time Limit: 1 sec

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