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Reverse a Singly Linked List

Reverse a Singly Linked List

Reverse the singly linked list and return the head of the reversed linked list.

We'll cover the following...

Statement

Given the head of a singly linked list, reverse the linked list and return its new or updated head.

Example

Consider the following linked list:

G rootptr head 7 7 rootptr->7 14 14 7->14 21 21 14->21 28 28 21->28 NULL NULL 28->NULL

Return the pointer to the reversed linked list as shown in the figure:

G rootptr head 28 28 rootptr->28 21 21 28->21 14 14 21->14 7 7 14->7 NULL NULL 7->NULL

Sample input

[7, 14, 21, 28]

Expected output

[28, 21, 14, 7]

Try it yourself #

main.cpp
LinkedList.cpp
LinkedListNode.cpp
#include "LinkedList.cpp"
using namespace std;
LinkedListNode* Reverse(LinkedListNode* head) {
	//TODO: Write - Your - Code
}

Solution 1

If the linked list only contains 0 or 1 node, then the current list can be returned as it is. If there are two or more nodes, then the iterative solution starts with two node pointers:

  • First pointer: points to the head of the input linked list.
  • Second pointer: It points to the head’s next node.

We then set the next of the first pointer to ...

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