Singly Linked List

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

// Node structure for singly linked list
class Node {
public:
    int data;       // Stores value
    Node* next;     // Pointer to next node

    // Constructor initializes data and next pointer
    Node(int data) {
        this->data = data;
        this->next = NULL;
    }
};

// Function to print the linked list
void printList(Node* head) {
    if(head == NULL) {
        cout << "List is Empty!" << endl;
        return;
    }

    cout << "Singly List : ";
    while(head != NULL) {
        cout << head->data << " ";
        head = head->next;  // Move to next node
    }
    cout << endl;
}

// Insert a node at the head (start) of the list
void insertAtHead(Node* &head, int data) {
    Node *temp = new Node(data); // Create new node
    temp->next = head;           // New node points to current head
    head = temp;                 // Head now points to new node
}

// Insert a node at the tail (end) of the list
void insertAtTail(Node* &tail, int data) {
    Node *temp = new Node(data); // Create new node
    tail->next = temp;           // Current tail points to new node
    tail = temp;                 // Tail now points to new node
}

// Insert a node at a specific position (1-based index)
void insertAtMiddle(Node* &head, Node* &tail, int data, int pos) {
    if(pos == 1) {  // Insert at head if position is 1
        insertAtHead(head, data);
        return;
    }

    Node *temp = head;
    // Traverse to (pos-1)th node
    while(temp != NULL && pos > 2) {
        temp = temp->next;
        pos--;
    }

    // If position is invalid
    if(temp == NULL || pos <= 0) {
        cout << "Invalid Position!" << endl;
        return;
    }

    // Insert new node after temp
    Node *insertNode = new Node(data);
    insertNode->next = temp->next;
    temp->next = insertNode;

    // Update tail if inserted at end
    if(insertNode->next == NULL) {
        tail = insertNode;
    }
}

// Delete a node at given position
void deletePosition(Node* &head, int pos) {
    Node *temp = head;

    // Deleting the first node
    if(pos == 1) {
        head = head->next;
        delete temp;
        return;
    }

    // Traverse to (pos-1)th node
    while(temp != NULL && pos > 2) {
        temp = temp->next;
        pos--;
    }

    // Check for invalid position
    if(temp == NULL || temp->next == NULL || pos <= 0) {
        cout << "Invalid Position!" << endl;
        return;
    }

    // Delete the node at position
    Node* target = temp->next;
    temp->next = target->next;
    delete target;
}

// Delete the first occurrence of a node with given value
void deleteValue(Node* &head, int val) {
    Node* temp = head->next;
    Node* prev = head;

    // If head node has the value
    if(head->data == val) {
        head = head->next;
        delete prev;
        return;
    }

    // Traverse to find node with matching value
    while(temp != NULL) {
        if(temp->data == val) {
            val = INT_MIN;  // Mark as found
            break;
        }
        prev = temp;
        temp = temp->next;
    }

    // If value not found
    if(prev->next == NULL || val != INT_MIN) {
        cout << "Value Not Found!" << endl;
        return;
    }

    // Delete the matching node
    prev->next = temp->next;
    delete temp;
}

int main() {
    Node *head = new Node(1);  // Initial head node with value 1
    Node *tail = head;         // Tail initially same as head

    // Insert powers of 2 (2 to 32) at tail
    for(int i = 1; i <= 5; i++) {
        insertAtTail(tail, pow(2, i));  // Inserts: 2, 4, 8, 16, 32
    }

    printList(head);  // Output: 1 2 4 8 16 32

    // Uncomment to test deleting by position
    // deletePosition(head, 6);
    // printList(head);

    deleteValue(head, 32);   // Deletes node with value 32
    printList(head);         // Output: 1 2 4 8 16

    return 0;
}

• Creating a singly linked list
• Inserting nodes at head, tail, or middle
• Deleting nodes by position or by value
• Printing the linked list

Singly List : 1 2 4 8 16 32
Singly List : 1 2 4 8 16

Function Name	Purpose
insertAtHead()	Insert node at beginning
insertAtTail()	Insert node at end
insertAtMiddle()	Insert node at specific position
deletePosition()	Delete node at given position
deleteValue()	Delete node by value
printList()	Print all nodes