﻿ C++ - Insert a node at any position of a Singly Linked List

# C++ Linked List Exercises: Insert a node at any position of a Singly Linked List

## C++ Linked List: Exercise-9 with Solution

Write a C++ program to insert a new node at any position of a Singly Linked List.

Test Data:
Original list:
7 5 3 1
Position: 1, Value: 12
Updated list:
12 7 5 3 1
Position: 4, Value: 14
Updated list:
12 7 5 14 3 1
Position: 7, Value: 18
Updated list:
12 7 5 14 3 1 18

Sample Solution:

C++ Code:

``````#include <iostream> // Including input-output stream header file

using namespace std; // Using standard namespace

// Structure for defining a Node
struct Node {
int num; // Data field to store a number
Node *next; // Pointer to the next node
}; // Node constructed

int sizen = 0; // Initializing variable to keep track of the size of the linked list

// Function to insert a node at the beginning of the linked list
void insert(Node** head, int num) {
Node* new_Node = new Node(); // Creating a new node
new_Node->num = num; // Assigning data to the new node
new_Node->next = *head; // Pointing the new node to the current head
sizen++; // Increasing the size of the linked list
}

// Function to insert a node at a given position in the linked list
void insert_Position(int pos, int data, Node** head) {
Node* new_node = new Node(); // Creating a new node
new_node->num = data; // Assigning data to the new node
new_node->next = NULL; // Initializing next pointer to NULL

// Invalid positions
if (pos < 1 || pos > sizen + 1) {
cout << "Invalid\n";
} else if (pos == 1) { // Inserting at the beginning
sizen++;
} else {
// Traverse till the (pos-1)th node
while (--pos > 1) {
temp = temp->next;
}
new_node->next = temp->next;
temp->next = new_node;
sizen++;
}
}

// Display all nodes in the linked list
void display_all_nodes(Node* node) {
while (node != NULL) {
cout << node->num << " "; // Displaying the data in the current node
node = node->next; // Move to the next node
}
}

int main() {

insert(&head, 1); // Inserting a node with value 1
insert(&head, 3); // Inserting a node with value 3
insert(&head, 5); // Inserting a node with value 5
insert(&head, 7); // Inserting a node with value 7

cout << "Original list:\n"; // Displaying message for the original list
display_all_nodes(head); // Displaying all nodes in the original list

int pos = 1, value = 12;
cout << "\n\nPosition: " << pos << ", Value: " << value;
insert_Position(pos, value, &head); // Inserting a node at a specific position
cout << "\nUpdated list:\n";
display_all_nodes(head); // Displaying all nodes in the updated list

pos = 4, value = 14;
cout << "\n\nPosition: " << pos << ", Value: " << value;
insert_Position(pos, value, &head); // Inserting a node at a specific position
cout << "\nUpdated list:\n";
display_all_nodes(head); // Displaying all nodes in the updated list

pos = 7, value = 18;
cout << "\n\nPosition: " << pos << ", Value: " << value;
insert_Position(pos, value, &head); // Inserting a node at a specific position
cout << "\nUpdated list:\n";
display_all_nodes(head); // Displaying all nodes in the updated list

cout << endl; // Displaying newline
return 0; // Returning from the main function
}
``````

Sample Output:

```Original list:
7 5 3 1

Position: 1, Value: 12
Updated list:
12 7 5 3 1

Position: 4, Value: 14
Updated list:
12 7 5 14 3 1

Position: 7, Value: 18
Updated list:
12 7 5 14 3 1 18
```

Flowchart:

CPP Code Editor: