Linked List

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

class node
{
public:
    int info;
    node *link;
};

node *head = NULL, *tmp = NULL;

void creation()
{
    node *ptr = new node();
    int item;
    cin>>item;
    ptr->info = item;
    ptr->link = NULL;
    if(head == NULL)
    {
        head = ptr;
        tmp = ptr;
    }
    else
    {
        tmp->link = ptr;
        tmp = ptr;
    }
}

void traverse()
{
    cout<<"The items in the list : ";
    node *srt;
    for(srt = head; ; )
    {
        if(srt->link != NULL)
        {
            cout<<srt->info<<" ";
            srt = srt->link;
        }
        else
        {
            cout<<srt->info;
            break;
        }
    }
    cout<<endl<<endl;
}

void first_insert()
{
    cout<<"Enter the item you want to inesrt : ";
    int item;
    cin>>item;
    node *ptr = new node();
    ptr->info = item;
    ptr->link = head;
    head = ptr;
}

void last_insert()
{
    cout<<"Enter the item you want to inesrt : ";
    int item;
    cin>>item;
    node *ptr = new node();
    ptr->info = item;
    ptr->link = NULL;
    node *srt;
    for(srt = head; ; )
    {
        if(srt->link == NULL)
        {
            srt->link = ptr;
            break;
        }
        else
        {
            srt = srt->link;
        }
    }
}

void before_insert()
{
    cout<<"Enter the 'before' value : ";
    int s_item;
    cin>>s_item;
    node *srt, *tmp;
    for(srt = head; ; )
    {
        if(srt->info == s_item)
        {
            if(srt == head)
            {
                first_insert();
                break;
            }
            else
            {
                cout<<"Enter the item you want to inesrt : ";
                int item;
                cin>>item;
                node *ptr = new node();
                ptr->info = item;
                ptr->link = NULL;
                tmp->link = ptr;
                ptr->link = srt;
                break;
            }
        }
        else
        {
            tmp = srt;
            srt = srt->link;
        }
        if(srt == NULL)
        {
            cout<<"'before' value not found."<<endl;
            break;
        }
    }
}

void after_insert()
{
    cout<<"Enter the 'after' value : ";
    int s_item;
    cin>>s_item;
    node *srt, *tmp;
    for(srt = head; ; )
    {
        if(srt->info == s_item)
        {
            if(srt->link == NULL)
            {
                last_insert();
                break;
            }
            else
            {
                cout<<"Enter the item you want to inesrt : ";
                int item;
                cin>>item;
                node *ptr = new node();
                ptr->info = item;
                ptr->link = srt->link;
                srt->link = ptr;
                break;
            }
        }
        else
        {
            tmp = srt;
            srt = srt->link;
        }
        if(srt == NULL)
        {
            cout<<"'before' value not found."<<endl;
            break;
        }
    }
}

int main()
{
    int i, n;
    cout<<"How many items you want to enter for creation : ";
    cin>>n;
    cout<<"Enter the items : ";
    for(i = 0; i < n; i++)
    {
        creation();
    }
    traverse();
    while(1)
    {
        int x;
        cout<<"Enter 1 for first insert \n Enter 2 for last insert \n Enter 3 for before insert \n Enter 4 for after insert  : ";
        cin>>x;
        cout<<endl;
        if(x == 1)
        {
            first_insert();
            traverse();
        }
        else if(x == 2)
        {
            last_insert();
            traverse();
        }
        else if(x == 3)
        {
            before_insert();
            traverse();
        }
        else if(x == 4)
        {
            after_insert();
            traverse();
        }
        else
        {
            cout<<"Please enter a number between 1 to 4 "<<endl;
        }
    }
    return 0;
}