package com.coding2017.basic.linklist;
import com.coding2017.basic.Iterator;
import com.coding2017.basic.List;
import java.util.Arrays;
import java.util.NoSuchElementException;
/**
* 功能:实现LinkedList.
*
* @author zhanglifeng.
*/
public class LinkedList implements List {
private Node head, tail;
private int size;
private Node getNodeByIndex(int index) {
if (index < 0 || index > size - 1) {
throw new IndexOutOfBoundsException("线性表索引越界");
}
Node current = head;
for (int i = 0; i < size && current != null; i++, current = current.next) {
if (i == index) {
return current;
}
}
return null;
}
public void add(Object o) {
addLast(o);
}
public void add(int index, Object o) {
if (index < 0 || index > size) {
throw new IndexOutOfBoundsException("线性表索引越界");
}
if (0 == index) {
addFirst(o);
} else {
Node node = getNodeByIndex(index - 1);
node.next = new Node(o, node.next);
size++;
}
}
public Object get(int index) {
return getNodeByIndex(index).data;
}
public Object remove(int index) {
if (index < 0 || index > size - 1) {
throw new IndexOutOfBoundsException("线性表索引越界");
}
if (0 == index) {
return removeFirst();
} else if (size - 1 == index) {
return removeLast();
} else {
Node node = getNodeByIndex(index);
Node preNode = getNodeByIndex(index - 1);
preNode.next = node.next;
size--;
return node.data;
}
}
public int size() {
return size;
}
public void addFirst(Object o) {
Node currentHead = head;
Node newNode = new Node(o, currentHead);
head = newNode;
if (currentHead == null) {
tail = newNode;
}
size++;
}
public void addLast(Object o) {
Node currentTail = tail;
Node newNode = new Node(o, null);
tail = newNode;
if (currentTail == null) {
head = newNode;
} else {
currentTail.next = newNode;
}
size++;
}
public Object removeFirst() {
if (head == null) {
throw new NoSuchElementException();
}
Node node = new Node(head.data, null);
head = head.next;
size--;
return node.data;
}
public Object removeLast() {
if (tail == null) {
throw new NoSuchElementException();
}
Node node = getNodeByIndex(size - 1);
node.next = null;
size--;
return node.data;
}
public Iterator iterator() {
return new LinkedListIterator(this);
}
private static class Node {
Object data;
Node next;
public Node(Object data, Node next) {
this.data = data;
this.next = next;
}
}
private class LinkedListIterator implements Iterator {
LinkedList linkedList = null;
private int current = 0;
public LinkedListIterator(LinkedList linkedList) {
this.linkedList = linkedList;
}
@Override
public boolean hasNext() {
return current < size;
}
@Override
public Object next() {
return linkedList.get(current++);
}
}
/**
* 把该链表逆置
* 例如链表为 3->7->10 , 逆置后变为 10->7->3
*/
public void reverse() {
Node first = head;
Node reverse = null;
while (first != null) {
Node second = first.next;
first.next = reverse;
reverse = first;
first = second;
}
head = reverse;
}
/**
* 删除一个单链表的前半部分
* 例如:list = 2->5->7->8 , 删除以后的值为 7->8
* 如果list = 2->5->7->8->10 ,删除以后的值为7,8,10
*/
public void removeFirstHalf() {
for (int i = 0; i < size / 2; i++) {
remove(i);
}
}
/**
* 从第i个元素开始, 删除length 个元素 , 注意i从0开始
*
* @param i
* @param length
*/
public void remove(int i, int length) {
if (size < i + length) {
throw new IndexOutOfBoundsException("线性表索引越界");
}
for (int j = i + length - 1; j >= i; j--) {
remove(j);
}
}
/**
* 假定当前链表和list均包含已升序排列的整数
* 从当前链表中取出那些list所指定的元素
* 例如当前链表 = 11->101->201->301->401->501->601->701
* listB = 1->3->4->6
* 返回的结果应该是[101,301,401,601]
*
* @param list
*/
public int[] getElements(LinkedList list) {
if (list.size() > size) {
throw new IndexOutOfBoundsException("线性表索引越界");
}
int[] array = new int[list.size];
for (int i = 0; i < array.length; i++) {
int element = (int) list.get(i);
if (element >= size) {
throw new IndexOutOfBoundsException("线性表索引越界");
}
array[i] = ((Integer) get(element));
}
System.out.println(Arrays.toString(array));
return array;
}
/**
* 已知链表中的元素以值递增有序排列,并以单链表作存储结构。
* 从当前链表中中删除在list中出现的元素
*
* @param list
*/
public void subtract(LinkedList list) {
int length = list.size();
for (int i = size - 1; i >= 0; i--) {
for (int j = 0; j < length; j++) {
if (get(i) == list.get(j)) {
remove(i);
break;
}
}
}
}
/**
* 已知当前链表中的元素以值递增有序排列,并以单链表作存储结构。
* 删除表中所有值相同的多余元素(使得操作后的线性表中所有元素的值均不相同)
*/
public void removeDuplicateValues() {
for (int i = size - 1; i > 0; i--) {
if (get(i) == get(i - 1)) {
remove(i);
}
}
}
/**
* 已知链表中的元素以值递增有序排列,并以单链表作存储结构。
* 试写一高效的算法,删除表中所有值大于min且小于max的元素(若表中存在这样的元素)
*
* @param min
* @param max
*/
public void removeRange(int min, int max) {
for (int i = size - 1; i >= 0; i--) {
int element = ((int) get(i));
if ((element > min) && element < max) {
remove(i);
}
}
}
/**
* 假设当前链表和参数list指定的链表均以元素依值递增有序排列(同一表中的元素值各不相同)
* 现要求生成新链表C,其元素为当前链表和list中元素的交集,且表C中的元素有依值递增有序排列
*
* @param list
*/
public LinkedList intersection(LinkedList list) {
LinkedList newList = new LinkedList();
int length = list.size();
for (int i = 0; i < size; i++) {
for (int j = 0; j < length; j++) {
if (get(i) == list.get(j)) {
newList.add(get(i));
break;
}
}
}
Iterator it = newList.iterator();
while (it.hasNext()) {
System.out.print(it.next() + " ");
}
System.out.println();
return newList;
}
public static void main(String[] args) {
LinkedList linkedList = new LinkedList();
linkedList.add(1);
linkedList.add(2);
linkedList.add(3);
linkedList.addFirst(0);
linkedList.addLast(4);
/*System.out.println("第3个元素:" + linkedList.get(3));
System.out.println(linkedList.removeFirst());
System.out.println(linkedList.size());
System.out.println("Last element:" + linkedList.removeLast());
System.out.println(linkedList.size());
System.out.println("第2个元素:" + linkedList.remove(2));*/
System.out.println(linkedList.size());
//linkedList.remove(0, 3);
LinkedList list = new LinkedList();
list.add(1);
list.add(3);
list.add(4);
//linkedList.getElements(list);
//linkedList.intersection(list);
linkedList.reverse();
Iterator it = linkedList.iterator();
while (it.hasNext()) {
System.out.print(it.next() + " ");
}
System.out.println();
}
}