﻿ C++ - Delete a middle node from a Singly Linked List

# C++ Linked List Exercises: Delete a middle node from a Singly Linked List

## C++ Linked List: Exercise-11 with Solution

Write a C++ program to delete a node from the middle of Singly Linked List.

Test Data:
Original list:
9 7 5 3 1
After removing the middle element of the said list:
9 7 3 1
After removing the middle element of the said list:
9 7 1
After removing the middle element of the said list:
9 1
After removing the middle element of the said list:
9

Sample Solution:

C++ Code:

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

using namespace std; // Using standard namespace

struct Node // Declare a structure for defining a 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 start of the linked list
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 remove the middle node of the linked list
if (head == NULL) // Base case: if the list is empty
return NULL;

if (head->next == NULL) { // Base case: if there's only one node in the list
return NULL;
}

Node* slow_ptr = head; // Pointer for slow traversal
Node* fast_ptr = head; // Pointer for fast traversal

Node* prev; // To store previous of slow_ptr
while (fast_ptr != NULL && fast_ptr->next != NULL) { // Loop to reach the middle of the linked list
fast_ptr = fast_ptr->next->next;
prev = slow_ptr;
slow_ptr = slow_ptr->next;
}

prev->next = slow_ptr->next; // Delete the middle node
delete slow_ptr; // Free memory allocated for the middle node
}

// Function to display all nodes in the linked list
void display_all_nodes(Node* node) {
while (node != NULL) { // Loop through all nodes until the end is reached
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
insert(&head,9); // Inserting a node with value 9

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

cout << "\nAfter removing the middle element of the said list:\n"; // Displaying message for removal of middle element
Node* result = get_Middle(head); // Removing the middle element of the list
display_all_nodes(result); // Displaying all nodes after removal

cout << "\nAfter removing the middle element of the said list:\n";
display_all_nodes(result);

cout << "\nAfter removing the middle element of the said list:\n";
display_all_nodes(result);

cout << "\nAfter removing the middle element of the said list:\n";
display_all_nodes(result);

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

Sample Output:

```Original list:
9 7 5 3 1
After removing the middle element of the said list:
9 7 3 1
After removing the middle element of the said list:
9 7 1
After removing the middle element of the said list:
9 1
After removing the middle element of the said list:
9
```

Flowchart:

CPP Code Editor: