convert function

convert.cpp

#include <iostream>
using namespace std;

struct tree_node{
    unsigned int data;
    tree_node *left = NULL;
    tree_node *right = NULL;
};

struct list_node{
	int data;
	list_node *next;
};

void print_list(list_node *head){
	if(head == NULL) cout << "EMPTY LIST";
	while(head){
		cout << head->data << " ";
		head = head->next;
	}
	cout << endl;
	
}

list_node* create_list_node(int value){
	list_node *new1 = new list_node;
    new1->data = value;
    new1->next = NULL;
    return new1;

}

void append_at_list(list_node *&head, int value){
	if(!head){ // if the head is null  
		head = create_list_node(value); 
		return; 
	}
	list_node *temp = head;
	while(temp->next)
		temp = temp->next;
	
	temp->next = create_list_node(value);
	
}


tree_node* create_tree_node(unsigned int x){
    tree_node *new1 = new tree_node;
    new1->data = x;
    new1->left = NULL;
    new1->right = NULL;
    return new1;
}

void insert_tree_node(tree_node *& t, unsigned int x){
    tree_node *temp1 = t, *temp2 = NULL;
    tree_node *new1 = create_tree_node(x);
    if(t == NULL){
        t = new1;
    }
    else{
        while(temp1 != NULL){
            temp2 = temp1;
            if(x <= temp1->data){
                temp1 = temp1->left;
            }
            else{
                temp1 = temp1->right;
            }
        }
        if(x <= temp2->data)
            temp2->left = new1;
        else
            temp2->right = new1;
    }
}

tree_node* convert(list_node *& L){ // L is the head of the list
	// L (will be destroyed) so we should make all nodes equal null;
	// but after taking the data from it
	tree_node *root = NULL;
	while(L){
		int data = L->data; // take the data in the list node
		insert_tree_node(root, data); // put the data in a tree node
		// now it's time to get rid of the list node
		// BUT first we should keep the next node in a temporary variable
		list_node *next_node = L->next; 
		delete L; // now we can delete the located space for the current node
		L = next_node; // let L equal the next_node; 
	}
	return root;
}

void printInorder(tree_node *t){
    if(t == NULL)
        return;
    if(t != NULL){
        printInorder(t->left);
        cout << t->data << " " ;
        printInorder(t->right);
    }
}

int main()
{
	list_node *head = NULL;
	append_at_list(head, 5);
	append_at_list(head, 1);
	append_at_list(head, 9);
	append_at_list(head, 2);
	append_at_list(head, 4);
	append_at_list(head, 6);
	append_at_list(head, 3);
	print_list(head);
	
	tree_node *root = convert(head);
	// this should print empty list because we destroyed all the nodes
	// (i.e.: delete them -- freed there space in memory)
	print_list(head); 
	printInorder(root);
    return 0;
}