Exercise_2.cpp

#include <bits/stdc++.h> 
using namespace std; 
 
// A structure to represent a stack 
class StackNode { 
public: 
 int data; 
 StackNode* next; 
}; 
 
StackNode* newNode(int data) 
{ 
 StackNode* stackNode = new StackNode(); 
 stackNode->data = data; 
 stackNode->next = NULL; 
 return stackNode; 
} 
 
int isEmpty(StackNode* root) 
{ 
 //Your code here 
} 
 
void push(StackNode** root, int data) 
{ 
 //Your code here 
} 
 
int pop(StackNode** root) 
{ 
 //Your code here 
} 
 
int peek(StackNode* root) 
{ 
 //Your code here 
} 
 
int main() 
{ 
 StackNode* root = NULL; 
 
 push(&root, 10); 
 push(&root, 20); 
 push(&root, 30); 
 
 cout << pop(&root) << " popped from stack\n"; 
 
 cout << "Top element is " << peek(root) << endl; 
 
 return 0; 
}