Solve problems that are commonly asked in C++ coding interviews related to common data structures.

Ace the C++ Coding Interview

Data structures are among the fundamentals of computer science and are often a core decision in developing efficient programs. They are categorized as a vital benchmark of computer science knowledge when it comes to industry interviews. This module contains a detailed review of common data structures in C++. We'll also become well-equipped with different data structures by implementing them.
By the end of this module, we'll have expertise in solving problems in data structures.

Data Structures

# Statement

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

**Constraints:**

Let `n` be the number of nodes in a linked list.

* $1 \leq$ `n` $\leq 5\times10^2$
* $-5\times10^3 \leq$ `Node.value` $\leq 5\times10^3$

# Solution
We will reverse the linked list without using any additional data structures by keeping track of the current, next, and previous nodes. By maintaining references to these nodes, we can iteratively traverse the linked list, updating the references as needed to reverse the order of the elements. This approach ensures that each node’s reference is correctly adjusted to point to its previous node, effectively reversing the linked list.



To reverse the linked list, we will follow these steps:

1. Initialize three pointers: `previous`, `nextNode`, and `current`. The `previous` and `nextNode` pointers are initialized as NULL, while the `current` pointer is initialized to the head of the linked list. 
2. Iterate over the linked list. While iterating, perform the following steps:
   -   Before changing the `next` pointer of `current`, store the next node in `nextNode` to prevent losing the reference to the rest of the list.
   -    Update the `next` pointer of `current` to point to the `previous` node. This effectively reverses the pointer of the current node.
   -    Move `previous` to `current` and `current` to `nextNode` to move to the next iteration.

3. After reversing the whole linked list, we’ll change the head pointer to the `previous` pointer because `previous` will be pointing to the new head node.

Let’s look at the following illustration to get a better understanding of reversing the linked list:

Let’s solve the Reverse Linked List problem.

Solution Review: Reverse a Linked List

Statement