lnklist

/* 1. head->next第一个元素, 位置为0
 * 2. setPos(-1) return head 
 * 3. 删除和插入先定位到前一个结点
 * 4. 尾结点为临界情况，需要特殊处理 */

#ifndef	LNKLIST_H
#define	LNKLIST_H

#include	<iostream>
using namespace std;

template<class T>
class Node {
public:
	T data;
	Node<T> *next;
	
	Node(const T info, Node<T> *nextValue = NULL) {
		data = info;
		next = nextValue;
	}
	
	Node(Node<T> *nextValue) {
		next = nextValue;
	}
};

template<class T>
class lnkList {
private:
	Node<T> *head, *tail;
	Node<T>* setPos(const int p);
	
public:
	lnkList(int s);
	~lnkList();
	void print();
	void clear();
	bool isEmpty();
	int	 length();
	bool getValue(const int p, T& value);
	bool setValue(const int p, const T value);
	bool getPos(int& p, const T value);
	bool append(const T value);
	bool insert(const int p, const T value);
	bool deletee(const int p);
};

/* 1. if para<-1, return false
 * 2. if para = -1, return head */
template<class T>
Node<T>* lnkList<T>::setPos(const int i) {
	if (i < -1) 
		return NULL;
	
	if (i == -1)
		return head;
	
	Node<T> *p = head->next;
	int count = 0;
	while (p != NULL && count < i) {
		p = p->next;
		count++;
	}
	
	return p;
}

// defSize????????
template<class T>
lnkList<T>::lnkList(int defSize = 0) {	
	head = tail = new Node<T>(0,NULL);
	cout<<"new empty list!"<<endl;
}

template<class T>
lnkList<T>::~lnkList() {
	Node<T> *tmp;
		
	while (head != NULL) {	
		tmp = head;	
		head = head->next;
		delete tmp;
	}
}

template<class T>
void lnkList<T>::print() {
	Node<T> *tmp = head->next;

	while (tmp != NULL) {
		cout<<tmp->data<<" ";
		tmp = tmp->next;
	}
	cout<<endl;
}

template<class T>
void lnkList<T>::clear() {
	Node<T> *tmp;
	while (head != NULL) {
		tmp = head;
		head = head->next;
		delete tmp;
	}
	
	head = tail = new Node<T>(0, NULL);
}


template<class T>
bool lnkList<T>::isEmpty() {
	if (head == tail) {
		cout<<"list is empty!"<<endl;
		return true;
	}
	
	return false;
}

template<class T>
int lnkList<T>::length() {
	int length = 0;	
	Node<T> *tmp = head->next;
	
	while (tmp != NULL) {
		length++;
		tmp = tmp->next;
	}

	return length;
}

template<class T>
bool lnkList<T>::setValue(const int i, const T value) {
	Node<T> *p;

	if ((p = setPos(i)) == NULL) {
		cout<<"illegal setvalue!"<<endl;
		return false;
	}

	p->data = value;

	return true;
}

template<class T>
bool lnkList<T>::getValue(const int i, T& value) {
	Node<T> *p;

	if ((p = setPos(i)) == NULL) {
		cout<<"illegal getvalue!"<<endl;
		return false;
	}

	value = p->data;

	return true;
}	

template<class T>
bool lnkList<T>::getPos(int &p, const T value) {
	Node<T> *q = head->next;
	
	for (int i = 0; i < length(); i++) {
		if (q->data == value) {
			p = i;
			return true;
		}
		
		q = q->next;
	}

	return false;
}	 

template<class T>
bool lnkList<T>::append(const T value) {
	Node<T> *p = new Node<T>(value, NULL);
	tail->next = p;
	tail = p;
	
	return true;
}

/* 1. if insertion illegal, cann't insert
 * 2. p指向插入前一个位置， p = setPos(i-1)
 * 3. q为新插入的结点，设置指针：q = p->next, p->next = q 
 * 4. if p is tail, tail = q */
template<class T>
bool lnkList<T>::insert(const int i, const T value) {
	Node<T> *p, *q;
	
	if (i < 0) { 
		cout<<"insertion illegal!"<<endl;
		return false;
	}

	if ((p = setPos(i-1)) == NULL) {
		cout<<"insertion illegal!"<<endl;
		return false;
	}

	q = new Node<T>(value, p->next);
	p->next = q;
	if (p == tail)
		tail = q;
	
	return true;
}

/* 1. if deletion illegal, cann't delete
 * 2. p指向删除前一个位置， p = setPos(i-1)
 * 3. q为待删除的结点， q = p->next
 * 4. if q is tail, tail = p, p->next = NULL, delete q
 * 5. p->next = q->next, delete q */
template<class T>
bool lnkList<T>::deletee(const int i) {
	Node<T> *p, *q;
	
	if ((p = setPos(i-1)) == NULL || p == tail) {
		cout<<"deletion illegal!"<<endl;
		return false;
	}

	q = p->next;

	if (q == tail) {	
		tail = p;
		p->next = NULL;
		delete q;
	}  
	else if (q != NULL) {
		p->next = q->next;
		delete q;
	}

	return true;
}

#endif

#include	<iostream>
#include	"lnklist.h"
using namespace std;

int
main() {
	lnkList<int> list(10);
	list.isEmpty();

	cout<<"init list 0-4"<<endl;
	for (int i = 0; i < 5; i++) 
		list.append(i);
	cout<<"The list is "<<(list.isEmpty()?"empty":"not empty")<<endl;
	cout<<list.length()<<endl<<"print the list:"<<endl;
	list.print();
	cout<<endl;	

	cout<<"insert(0,5) (3, 5) (7, 5) (9, 5) (-3, 0)"<<endl;
	list.insert(0, 5); list.print();
	list.insert(3, 5); list.print();
	list.insert(7, 5); list.print();
	list.insert(9, 5); list.print();
	list.insert(-3, 0); list.print();
	cout<<endl;

	cout<<"setvalue(4, 5) (0, 7) (7, 80) (-4, 5) (33, 5)"<<endl;
	list.setValue(4, 5);
	list.setValue(0, 7);
	list.setValue(7, 80);
	list.setValue(-4, 5);
	list.setValue(33, 5);
	list.print();
	cout<<endl;

	cout<<"getvalue 0-curLen"<<endl;
	int v;	
	for (int i = 0; i < list.length(); i++) {
		list.getValue(i, v);
		cout<<v<<" ";
	}
	cout<<endl;

	cout<<"getpos 4, 5"<<endl;
	int p;
	list.getPos(p, 4);
	cout<<p<<" ";
	list.getPos(p, 5);
	cout<<p<<endl<<endl;

	cout<<"delete 0, 3, 5 -3, 9"<<endl;
	list.deletee(0);
	list.print();
	list.deletee(3);
	list.deletee(5);
	list.print();
	list.deletee(-3);
	list.deletee(9);
	cout<<endl;

	list.clear();
	list.isEmpty();

	return 0;
}