[자료구조] 단일 연결리스트

#include 
#include 
//*******************************************************************
// 단일 연결리스트 구현  - head노드만 !! 
//*******************************************************************
struct Node
{
	int Data; // 데이타 저장소 
	Node * next;  //  다음 노드를 가르킬 포인터 
};
//*******************************************************************
Node * head; 
//*******************************************************************
// CreateNode : 노드 생성 
//*******************************************************************

Node * CreateNode( int data) 
{
	Node * NewNode = (Node*)malloc(sizeof(Node)); 
	NewNode->Data = data;
	NewNode->next =NULL;
	return NewNode; 
}
//*******************************************************************
// init
//*******************************************************************
void Init()
{
	head =  CreateNode(0);
	head->next = NULL; 
}

//*******************************************************************
void push_front(int data)
{
	Node * NewNode  = CreateNode(data);
	if( head->next == NULL)
	{
		head->next = NewNode;
	}
	else 
	{
		NewNode->next = head->next;
		head->next = NewNode; 
	}
}
//*******************************************************************
void push_back(int data) 
{
	Node * NewNode = CreateNode(data);
	Node * p =  head; 
	while( p->next != NULL)
	{
		p = p->next; 
	}
	NewNode->next = p->next;
	p->next = NewNode;
}
//*******************************************************************
void Insert(int key, int data)
{	
	Node * NewNode = CreateNode(data);

	Node * p = head->next; 
	while( p != NULL)
	{
		if( p->Data == key) 
		{
			NewNode->next = p->next; 
			p->next =  NewNode; 
			return;
		}
		else
		{
			p = p->next;
		}
	}
	free(NewNode);
	push_back(data);
}

//-----------------------------------------------------------------
// 맨뒤에서 삭제 
//-----------------------------------------------------------------
void pop_back() 
{
	Node * p, *s; 
	
	if( head->next == NULL) 
	{
		puts("list Empty ~ !!"); return; 
	}
	else 
	{
		p = head->next;
		s = head; 
		while( p->next != NULL)
		{
			s = p;
			p = p->next;
		}
		s->next = p->next; 
		free(p);
	}
}
//-----------------------------------------------------------------
//-----------------------------------------------------------------
//  중간에서 삭제 !! 
//-----------------------------------------------------------------
void erase( int key)
{	
	Node * p, *s; 
	if( head->next == NULL) 
	{
		puts("list empty !!");
	}
	else
	{
		s = head;
		p = head->next;
		while( p != NULL) 
		{
			if( p->Data == key) 
			{
				s->next = p->next;
				free(p); 
				return;
			}
			else
			{
				s = p;
				p = p->next;
			}
			
		}
	} 
}
// 전체 삭제
void clear()
{
	Node * p, * s;
	if(head->next ==NULL)
	{
		puts("List Empty~!!");
		free(head);
		puts("노드 없었던거.Disappeared !!");
		return;
	}
	else
	{
		while(head->next!= NULL)
		{
		
			p = head->next;
			s= head;
			while(p->next!=NULL)
			{
				s=p;
				p=p->next;
			}
			s->next = p->next;
			free(p);
		
		}
		free(head);
		puts("노드 있었던거.Disappeared !!");
		return;
	}
}

//to.위에 코드 짜신분
//  - 이건 어때여
//void clear()
//{
//	while(head->next != NULL)
//	{
//		pop_back();
//	}
//	printf("clear!");
//} // 전체 삭제 !!  


//void clear() // 전체삭제
//{
//	Node *p = head->next;
//	while(p!=NULL)
//	{
//		head->next = p->next;
//		free(p);
//		p = head->next;
//	}
//} 


void pop_front()
{	Node * p;
	if( head->next == NULL)
	{
		puts("list empty !! ");
	}
	else
	{
		p = head->next;
		head->next = p->next;
		free(p); 
	}
}

void Show()
{
	Node * p = head->next; 
	while( p != NULL) 
	{	
		printf("%d --> " ,  p->Data );
		p = p ->next;
	}
	puts(""); //개행
}
//*******************************************************************
void main()
{
	Init(); 

	push_front(10);
	push_front(20);
	push_front(30);
	Show();
	pop_front();
	Show();
	pop_front();
	Show();
	pop_front();
	Show();
	clear();


}