Stack Data Structure

Similar with: Queue, but LIFO

#include <bits/stdc++.h>
using namespace std;
 
class StackNode
{
public:
    int data;
    StackNode *next;
};
 
StackNode *newNode(int data)
{
    StackNode *Node = new StackNode();
    Node->data = data;
    Node->next = nullptr;
    return Node;
}
 
bool isEmpty(StackNode *root)
{
    return root == nullptr;
}
 
void push(StackNode **root, int data)
{
    StackNode *nNode = newNode(data);
    nNode->next = *root;
    *root = nNode;
    cout << data << " pushed to stack\n";
}
 
int pop(StackNode **root)
{
    if (isEmpty(*root))
    {
        return -1;
    }
    StackNode *temp = *root;
    *root = (*root)->next;
    int data = temp->data;
    delete temp;
    return data;
}
 
int peek(StackNode *root)
{
    if (isEmpty(root))
    {
        return -1;
    }
 
    return root->data;
}
 
int main()
{
    StackNode *root = nullptr;
    push(&root, 10);
    push(&root, 20);
    push(&root, 40);
    cout << "Top element is " << peek(root) << endl;
 
    while (!isEmpty(root))
    {
        cout << peek(root) << " ";
        pop(&root);
    }
}