#include <stdio.h>
#include <stdlib.h>
struct node
{
    struct node *left;
    struct node *right;
    int data;
};

struct stack
{
    struct node *data;
    struct stack *next;
};

void push(struct stack **top, struct node *n);
struct node *pop(struct stack **top);
int isEmpty(struct stack *top);

int tree_traversal(struct node *root)
{
    struct node *temp = root;
    struct stack *s_temp = NULL;
    int flag = 1;
    while (flag)
    {
        if (temp)
        {
            printf("%d ", temp->data);
            push(&s_temp, temp);
            temp = temp->left;
        }
        else
        {
            if (!isEmpty(s_temp))
            {
                temp = pop(&s_temp);
                temp = temp->right;
            }
            else
                flag = 0;
        }
    }
}

void push(struct stack **top, struct node *n)
{
    struct stack *new_n = (struct stack *)malloc(sizeof(struct stack));
    new_n->data = n;
    new_n->next = (*top);
    (*top) = new_n;
}

int isEmpty(struct stack *top)
{
    if (top == NULL)
        return 1;
    else
        return 0;
}

struct node *pop(struct stack **top_n)
{
    struct node *item;
    struct stack *top;
    top = *top_n;
    item = top->data;
    *top_n = top->next;
    free(top);
    return item;
}

struct node *create_node(int data)
{
    struct node *new_n = (struct node *)malloc(sizeof(struct node));
    new_n->data = data;
    new_n->left = NULL;
    new_n->right = NULL;
    return (new_n);
}

int main()
{
    struct node *root;
    root = create_node(8);
    root->left = create_node(5);
    root->right = create_node(4);
    root->left->left = create_node(7);
    root->left->right = create_node(6);
    tree_traversal(root);
    return 0;
}