Linked_List.cpp

#include <iostream>

using namespace std;

struct node
{
    int data;
    node *next;
} *head = NULL;

bool Is_List_Empty()
{
    if(head == NULL)
        return true;

    return false;
}

void Insert_At_Beginning(int value)
{
    node *temp = new node;
    temp -> data = value;
    temp -> next = head;
    head = temp;
}

void Insert_At_End(int value)
{
    node *temp = new node, *current = head;
    temp -> data = value;
    temp -> next = NULL;

    if(Is_List_Empty())
    {
        head = temp;
        return ;
    }

    while(current -> next != NULL)
        current = current -> next;

    current -> next = temp;
}

void Insert_After_Value(int desired, int value)
{
    node *current = head;

    while(current != NULL && current -> data != desired)
        current = current -> next;

    if(current == NULL)
        cout << "Element " << desired << " is not in list" << endl;
    else
    {
        node *temp = new node;
        temp -> data = value;
        temp -> next = current -> next;
        current -> next = temp;
    }
}

void Delete_At_Beginning()
{
    if(Is_List_Empty())
        cout << "List is empty" << endl;
    else
    {
        node *temp = head;
        head = head -> next;
        temp -> next = NULL;
        delete temp;
    }
}

void Delete_At_End()
{
    if(Is_List_Empty())
    {
        cout << "List is empty" << endl;
        return ;
    }

    node *temp = head, *prev;

    if(head -> next == NULL)
    {
        head = NULL;
        delete temp;
        return ;
    }

    while(temp -> next != NULL)
    {
        prev = temp;
        temp = temp -> next;
    }

    prev -> next = temp -> next;
    temp -> next = NULL;
    delete temp;
}

void Delete_With_Value(int desired)
{
    if(Is_List_Empty())
    {
        cout << "List is empty" << endl;
        return ;
    }

    node *temp = head, *prev;

    if(head -> data == desired)
    {
        head = head -> next;
        temp -> next = NULL;
        delete temp;
        return ;
    }

    while(temp != NULL && temp -> data != desired)
    {
        prev = temp;
        temp = temp -> next;
    }

    if(temp == NULL)
        cout << "Element " << desired << " not in list" << endl;
    else
    {
        prev -> next = temp -> next;
        temp -> next = NULL;
        delete temp;
    }
}

void Search(int desired)
{
    node *temp = head;

    while(temp != NULL && temp -> data != desired)
        temp = temp -> next;

    if(temp == NULL)
        cout << "Element " << desired << " not found" << endl;
    else
        cout << "Element " << desired << " is present in list" << endl;
}

void Print_Linked_List()
{
    if(Is_List_Empty())
    {
        cout << "List is Empty" << endl;
        return ;
    }

    node *current = head;

    while(current -> next != NULL)
    {
        cout << current -> data << " -> ";
        current = current -> next;
    }

    cout << current -> data << endl;
}

int main()
{
    int i;

    for(i = 0; i < 5; i++)
        Insert_At_Beginning(i);

    Print_Linked_List();

    for(i = 5; i < 10; i++)
        Insert_At_End(i);

    Print_Linked_List();

    Insert_After_Value(5, 9);
    Insert_After_Value(10, 9);

    Print_Linked_List();

    for(i = 0; i < 3; i++)
        Delete_At_End();

    Print_Linked_List();

    for(i = 0; i < 3; i++)
        Delete_At_Beginning();

    Print_Linked_List();

    Delete_With_Value(1);
    Delete_With_Value(5);

    Print_Linked_List();

    Search(6);
    Search(8);

    return 0;
}

/*  Output
    4 -> 3 -> 2 -> 1 -> 0
    4 -> 3 -> 2 -> 1 -> 0 -> 5 -> 6 -> 7 -> 8 -> 9
    Element 10 is not in list
    4 -> 3 -> 2 -> 1 -> 0 -> 5 -> 9 -> 6 -> 7 -> 8 -> 9
    4 -> 3 -> 2 -> 1 -> 0 -> 5 -> 9 -> 6
    1 -> 0 -> 5 -> 9 -> 6
    0 -> 9 -> 6
    Element 6 is present in list
    Element 8 not found
*/