/*
// Lesson 13, pointers and dynamic memory
//
//
// lists of nodes should look like this
//
// [data]->[data]->[data]->[data]->[data]->NULL
// 
// in this exercise you will implement functions to add nodes to the end of the list
// and remove nodes from the end of the list.
// 
// the data in this exercise are simple ints. when creating new nodes use the getnum() function to fill the data.
//
// when everything works you should be able to add as many elements as you want, and remove elements back to zero.
//
// Fun Fact: this is a more simple version of an excercise you will be required to do one day in any programming course and many interviews.
//
*/

#include <iostream>

/////////////////////////////////
//define objects here

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

//////////////////////////////////
//place function declarations here

void insert(node** root);
void remove(node** root);
void display(node* root);
int getsize(node* root);
int getnum();

//////////////////////////////////
//main program (do not modify)
int main(int argc, char** argv)
{
	bool done = false;
	node* list = NULL;

	while( !done )
	{
		int choice;
		std::cout<<"\n\n========choices========\n";
		std::cout<<"1. add a random number to the end of the list\n";
		std::cout<<"2. remove a number from the end of the list\n";
		std::cout<<"3. display the list\n";
		std::cout<<"4. display the size of the list\n";
		std::cout<<"0. quit\n";
		std::cout<<"please choose an option: ";
		std::cin>>choice;
		std::cout<<"\n--------------------------\n";
		
		switch(choice)
		{
			case 0: done = true; break;
			case 1: 
				insert(&list);
			break;
			case 2:
				remove(&list);
			break;
			case 3:
				display(list);
			break;
			case 4:
				std::cout<<"the list size is "<<getsize(list)<<std::endl;
			break;
			default: break;
		}
	}

	while( list )
	{
		node* next = list->next;
		delete list;
		list = next;
	}

	return 0;
}



//////////////////////////////////
//place function definitions here

void insert(node** root)
{
	//TODO: your code here
	node* temp = *root;
	if(*root)
	{
		while((*root)->next)
		{
			(*root) = (*root)->next;
		}
		(*root)->next = new node;
		(*root)->next->data = getnum();
		(*root)->next->next = 0;
		*root = temp;
	}
	else
	{
		(*root) = new node;
		(*root)->data = getnum();
		(*root)->next = 0;
	}

}

void remove(node** root)
{
	//TODO: your code here
	node* temp = *root;
	node* previous = 0;
	if(*root)
	{
		while((*root)->next)
		{
			previous = *root;
			*root = (*root)->next;
		}
		delete *root;
		*root = temp;
		if(previous)
		{
			previous->next = 0;
		}
	}
	else
	{
		std::cout<<"cannot delete items from empty list\n";
	}
}

void display(node* root)
{
	//TODO: your code here
	if(root)
	{
		while(root)
		{
			std::cout<<root->data<<"\n";
			root = root->next;
		}
	}
	else
	{
		std::cout<<"list is currently empty\n";
	}
}

int getsize(node* root)
{
	int size = 0;

	//TODO: your code here
	if(root)
	{
		while(root)
		{
			++size;
			root = root->next;
		}
	}
	else
	{
		return 0;
	}
	
	return size;
}

#include <cstdlib>
int getnum()
{ return rand()%100; }