Program to solve Tower of Hanoi C++ using Stack

Program to solve Tower of Hanoi C++ using Stack

#include<stdio.h>
#include<iostream>
#include<math.h>
using namespace std;
struct node1
{
    int data1;
    node1 *next1;
}*top1 = NULL, *p1 = NULL, *np1 = NULL;
struct node2
{
    int data2;
    node2 *next2;
}*top2 = NULL, *p2 = NULL, *np2 = NULL;
struct node3
{
    int data3;
    node3 *next3;
}*top3 = NULL, *p3 = NULL, *np3 = NULL;
void push1(int data)
{
    np1 = new node1;
    np1->data1 = data;
    np1->next1 = NULL;
    if (top1 == NULL)
    {
        top1 = np1;
    }
    else
    {
        np1->next1 = top1;
        top1 = np1;
    }
}
int pop1()
{
    int b = 999;
    if (top1 == NULL)
    {
        return b;
    }
    else
    {
        p1 = top1;
        top1 = top1->next1;
        return(p1->data1);
        delete(p1);
    }
}
void push2(int data)
{
    np2 = new node2;
    np2->data2 = data;
    np2->next2 = NULL;
    if (top2 == NULL)
    {
        top2 = np2;
    }
    else
    {
        np2->next2 = top2;
        top2 = np2;
    }
}
int pop2()
{
    int b = 999;
    if (top2 == NULL)
    {
        return b;
    }
    else
    {
        p2 = top2;
        top2 = top2->next2;
        return(p2->data2);
        delete(p2);
    }
}
void push3(int data)
{
    np3 = new node3;
    np3->data3 = data;
    np3->next3 = NULL;
    if (top3 == NULL)
    {
        top3 = np3;
    }
    else
    {
        np3->next3 = top3;
        top3 = np3;
    }
}
int pop3()
{
    int b = 999;
    if (top3 == NULL)
    {
        return b;
    }
    else
    {
        p3 = top3;
        top3 = top3->next3;
        return(p3->data3);
        delete(p3);
    }
}
int top_of_stack()
{
    if (top1 != NULL && top1->data1 == 1 )
    {
        return 1;
    }
    else if (top2 != NULL && top2->data2 == 1)
    {
        return 2;
    }
    else if (top3 != NULL && top3->data3 == 1)
    {
        return 3;
    }
}
void display1()
{
    cout<<endl;
    node1 *p1;
    p1 = top1;
    cout<<"Tower1-> "<<"t";
    while (p1 != NULL)
    {
        cout<<p1->data1<<"t";
        p1 = p1->next1;
    }
    cout<<endl;
}
void display2()
{
    node2 *p2;
    p2 = top2;
    cout<<"Tower2-> "<<"t";
    while (p2 != NULL)
    {
        cout<<p2->data2<<"t";
        p2 = p2->next2;
    }
    cout<<endl;
}
void display3()
{
    node3 *p3;
    p3 = top3;
    cout<<"Tower3-> "<<"t";
    while (p3 != NULL)
    {
        cout<<p3->data3<<"t";
        p3 = p3->next3;
    }
    cout<<endl;
    cout<<endl;
}
void toh(int n)
{
    int i, x, a, b;
    for (i = 0; i < (pow(2,n)); i++)
    {
        display1();
        display2();
        display3();
        x = top_of_stack();
        if (i % 2 == 0)
        {
            if (x == 1)
            {
                push3(pop1());
            }
            else if (x == 2)
            {
                push1(pop2());
            }
            else if (x == 3)
            {
                push2(pop3());
            }
        }
        else
        {
            if (x == 1)
            {
                a = pop2();
                b = pop3();
                if (a < b && b != 999)
                {
                    push3(b);
                    push3(a);
                }
                else if (a > b && a != 999)
                {
                    push2(a);
                    push2(b);
                }
                else if (b == 999)
                {
                    push3(a);
                }
                else if (a == 999)
                {
                    push2(b);
                }
            }
            else if (x == 2)
            {
                a = pop1();
                b = pop3();
                if (a < b && b != 999)
                {
                    push3(b);
                    push3(a);
                }
                else if (a > b && a != 999)
                {
                    push1(a);
                    push1(b);
                }
                else if (b == 999)
                {
                    push3(a);
                }
                else if (a == 999)
                {
                    push1(b);
                }
            }
            else if (x == 3)
            {
                a = pop1();
                b = pop2();
                if (a < b && b != 999)
                {
                    push2(b);
                    push2(a);
                }
                else if (a > b && a != 999)
                {
                    push1(a);
                    push1(b);
                }
                else if (b == 999)
                {
                    push2(a);
                }
                else if (a == 999)
                {
                    push1(b);
                }
            }
        }
    }
}
int main()
{
    int n, i;
    cout<<"enter the number of disksn";
    cin>>n;
    for (i = n; i >= 1; i--)
    {
        push1(i);
    }
    toh(n);
    return 0;
}