#include<stdio.h>
#include<stdlib.h>
struct node
{
	int data;
	struct node *left;
	struct node *right;
};
struct node *root=NULL;
struct node *create(int item);
void postorder(struct node *root);
void preorder(struct node *root);

int main()
{
	struct node *root=create(11);
	root->left=create(22);
	root->right=create(33);
	root->left->left=create(44);
	root->left->right=create(55);
	root->right->left=create(66);
	root->right->right=create(77);

	printf("postorder traversal result\n");
		postorder(root);
	printf("\n");
	printf("preorder traversal result\n");
		preorder(root);
}
struct node *create(int item)
{
	struct node *temp;
	temp=(struct node*)malloc(sizeof(struct node));
	temp->data=item;
	temp->left=NULL;
	temp->right=NULL;
	return temp;
}
void postorder(struct node *root)
{
	struct node *stack[20],*ptr;
	int top=-1;
	ptr=root;
	while(1)
	{
		if(ptr!=NULL)
		{
			stack[++top]=ptr;
			ptr=ptr->left;
		}
		else
		{
			if(top==-1)
			break;
			else
			{
				if(stack[top]->right==NULL)
				{
					ptr=stack[top--];
					printf("%d ",ptr->data);
					while(ptr==stack[top]->right)
					{
						printf("%d ",stack[top]->data);
						ptr=stack[top--];
						if(top==-1)
						break;
					}
				}
				if(top!=-1)
					ptr=stack[top]->right;
				else
					ptr=NULL;
			}
		}

	}

}
void preorder(struct node *root)
{
	struct node *ptr,*stack[20];
	int top=-1;
	ptr=root;
	while(1)
	{
		while(ptr!=NULL)
			{
				printf("%d ",ptr->data);
				stack[++top]=ptr;
				ptr=ptr->left;
			}
			if(top==-1)
				break;
			else
			{
				ptr=stack[top--];
				ptr=ptr->right;
			}
	}
}