Checking whether entered singly list is palindrome or not but it showing error that data and next is not declared

Question

include<iostream>

include<bits/stdc++.h>

using namespace std;
class node{
public:
int size;
node()
{
cout<<"Enter the size of aarray : ";
cin>>size;

}

};
template<class T>
class array:public node{
public:
int data,choice=1,tem;
node *newnode;
node next;
bool isPalin(int data,node *head,int next);
node head;
array()
{
while(choice)
{
head=0;
newnode=(node)new(sizeof(node));
cout<<"Enter data ";
cin>>data;
&newnode->data;
&newnode->next=0;
if(head==0)
{
head=tem=newnode;
}
else
{
tem->next=newnode;
tem=newnode;
}
cout<<"Want to enter next node";
cin>>choice;
}

}  

};
template<class T>
bool array<T> :: isPalin(int* data,int* next){
node* slow= head; // Temp pointer
stack <int> s; // Declare a stack
while(slow != NULL){ // Push all elements of the list to the stack
s.push(slow->data);
slow = slow->next; // Move ahead
}
while(head != NULL ){ // Iterate in the list again and check by popping from the stack
int i=s.top(); // Get the top most element
s.pop(); // Pop the element
if(head -> data != i) // Check if data is not same as popped element
{
return false;
}
head=head->next; // Move ahead
}
return true;
}
int main()
{
array<bool>l;
l.isPalin(l.data,l.next) ;
}

Answer 1

Hi @Stuti Thakur ,

I understand what you mean. Actually, templates are not needed all the time. I modified your code, you could refer to it.

#include<iostream>  
#include<vector>  
#include<stack>  
using namespace std;  
class arr {  
public:  
 int n, a;  
 arr* next;  
 arr* tem;  
 arr* head = nullptr;  
 int data, choice = 1;  
 bool isPalin();  
 void create()  
 {  
 while (choice)  
 {  
 arr* NewNode;  
 NewNode = new arr;  
 cout << "Enter data ";  
 cin >> data;  
 NewNode->data = data;  
 NewNode->next = nullptr;  
 /*head->next = NewNode;*/  
 if (head == nullptr)  
 {  
 head = NewNode;  
 tem = NewNode;  
 }  
 else  
 {  
 tem->next = NewNode;  
 tem = NewNode;  
 }  
 cout << "Want to enter next number";  
 cin >> choice;  
 }  
 }  
};  
bool arr::isPalin() {  
 arr* slow = head; // Temp pointer  
 stack <int> s; // Declare a stack  
 while (slow != NULL) { // Push all elements of the list to the stack  
 s.push(slow->data);  
 slow = slow->next; // Move ahead  
 }  
 while (head != NULL) { // Iterate in the list again and check by popping from the stack  
 int i = s.top(); // Get the top most element  
 s.pop(); // Pop the element  
 if (head->data != i) // Check if data is not same as popped element  
 {  
 return false;  
 }  
 head = head->next; // Move ahead  
 }  
 return true;  
}  
int main()  
{  
 arr l;  
 l.create();  
 if (l.isPalin())  
 cout << "yes";  
 else  
 cout << "no";  
}  

Best regards,

Elya

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