# Reverse a Linked List Hackerrank Solution | Data Structures

Reverse a Linked List Hackerrank Solution in C++Given the pointer to the head node of a linked list, change the next pointers of the nodes so that their order is reversed. The head pointer given may be null meaning that the initial list is empty.

Example

head references the list 1 -> 2 -> 3 -> NULL

Manipulate the next pointers of each node in place and return the head, now referencing the head of the list 3 -> 2 -> 1 -> NULL.

Function Description

Complete the reverse function in the editor below.

reverse has the following parameter:

Returns

Input Format

The first line contains an integer t, the number of test cases.

Each test case has the following format:

The first line contains an integer n, the number of elements in the linked list.
Each of the next n lines contains an integer, the data values of the elements in the linked list.

Constraints

1 <= t <= 10
1 <= n <= 1000
1 <= list[i] <= 10, where list[i] is the ith element in the list.

Sample Input

1
5
1
2
3
4
5

Sample Output

5 4 3 2 1

Explanation

The initial linked list is 1 -> 2 -> 3 -> 4 -> 5 -> NULL.

The reversed linked list is: 5 -> 4 -> 3 -> 2 -> 1 -> NULL.

## Reverse a Linked List Hackerrank Solution in C++

``````#include <bits/stdc++.h>
using namespace std;

{
public:
int data;

{
this->data = node_data;
this->next = nullptr;
}
};

{
public:

{
this->tail = nullptr;
}

void insert_node(int node_data)
{

{
}
else
{
this->tail->next = node;
}

this->tail = node;
}
};

{
while (node)
{
fout << node->data;

node = node->next;

if (node)
{
fout << sep;
}
}
}

{
while (node)
{
node = node->next;

free(temp);
}
}

/*
*Complete the 'reverse' function below.
*
*The function is expected to return an INTEGER_SINGLY_LINKED_LIST.
*The function accepts INTEGER_SINGLY_LINKED_LIST llist as parameter.
*/

/*
*
*    int data;
*};

*
*/

{
while (present != nullptr)
{
future = present->next;
present->next = past;
past = present;
present = future;
}

return past;
}

int main()
{
ofstream fout(getenv("OUTPUT_PATH"));

int tests;
cin >> tests;
cin.ignore(numeric_limits<streamsize>::max(), '\n');

for (int tests_itr = 0; tests_itr < tests; tests_itr++)
{

int llist_count;
cin >> llist_count;
cin.ignore(numeric_limits<streamsize>::max(), '\n');

for (int i = 0; i < llist_count; i++)
{
int llist_item;
cin >> llist_item;
cin.ignore(numeric_limits<streamsize>::max(), '\n');

llist->insert_node(llist_item);
}

fout << "\n";

}

fout.close();

return 0;
}``````

### Reverse a Linked List Explanation

Before solving this problem (reverse a linked list) first, see how linked list work for better understand this problem I have created a Full Code of a Reverse Linked List so you can understand very well First check the full code and test. After that see the hacker rank solution for reverse a linked list function or segment, and paste that coloured code in the editor for a successfully compiled solution.

### The Output of Reverse a Linked List Hackerrank Solution

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#### post written by: Ghanendra Yadav

Hi, I’m Ghanendra Yadav, SEO Expert, Professional Blogger, Programmer, and UI Developer. Get a Solution of More Than 500+ Programming Problems, and Practice All Programs in C, C++, and Java Languages. Get a Competitive Website Solution also Ie. Hackerrank Solutions and Geeksforgeeks Solutions. If You Are Interested to Learn a C Programming Language and You Don't Have Experience in Any Programming, You Should Start with a C Programming Language, Read: List of Format Specifiers in C.