package com.coding.basic.linklist;
import com.coding.basic.Iterator;
import com.coding.basic.List;
public class LinkedList implements List {
private Node head;
private int size = 0;
public void add(Object o) {
Node newNode = new Node(o, null);
if (head == null) {
head = newNode;
} else {
node(size - 1).next = newNode;
}
size++;
}
public void add(int index, Object o) {
checkForAdd(index);
if (index == size) {
add(o);
} else {
Node newNode = new Node(o, null);
if (index == 0) {
addFirst(o);
} else {
Node preNode = node(index - 1);
Node now = preNode.next;
preNode.next = newNode;
newNode.next = now;
size++;
}
}
}
private Node node(int index) {
Node x = head;
for (int i = 0; i < index; i++) {
x = x.next;
}
return x;
}
public Object get(int index) {
checkIndex(index);
return node(index).data;
}
/**
* 让被删除的引用的持有者指向下一个节点
*
* @param index
* @return
*/
public Object remove(int index) {
final Object ret;
checkIndex(index);
if (index == 0) {
Node removeNode = head;
ret = head.data;
head = removeNode.next;
} else {
Node pre = node(index - 1);
Node removeNode = pre.next;
ret = removeNode.data;
pre.next = removeNode.next;
}
size--;
return ret;
}
public int size() {
return size;
}
public void addFirst(Object o) {
head = new Node(o, head);
;
size++;
}
public void addLast(Object o) {
add(o);
}
public Object removeFirst() {
if (size == 0) {
return null;
} else {
return remove(0);
}
}
public Object removeLast() {
return remove(size - 1);
}
public LinkedListIterator iterator() {
return new LinkedListIterator(head);
}
private void checkIndex(int index) {
if (index < 0 || index >= size) {
throw new ArrayIndexOutOfBoundsException(String.format("index=%s, size=%s", index, size));
}
}
private void checkForAdd(int index) {
if (index < 0 || index > size) {
throw new ArrayIndexOutOfBoundsException(String.format("index=%s, size=%s", index, size));
}
}
@Override
public String toString() {
Iterator iterator = iterator();
StringBuilder builder = new StringBuilder("[");
while ((iterator.hasNext())) {
builder.append(iterator.next()).append(',');
}
if (size() > 0) {
builder.deleteCharAt(builder.length() - 1);
}
return builder
.append(']')
.toString();
}
/**
* 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() {
if (size == 0) {
return;
}
Object[] datas = new Object[size];
int i = 0;
// 迭代链表的数据生成数组
Iterator iterator = iterator();
while (iterator.hasNext()) {
datas[i++] = iterator.next();
}
// 遍历数组越生成新的 链表
Node newHead = new Node(datas[--i], null);
Node next = newHead;
for (int j = --i; j >= 0; j--) {
next.next = new Node(datas[j], null);
next = next.next;
}
this.head = newHead;
}
/**
* 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() {
removeFirstSize(size >> 1);
}
public void removeFirstSize(int firstSize) {
firstSize = firstSize > size() ? size() : firstSize;
LinkedListIterator iterator = iterator();
int i = 1;
while (i++ <= firstSize) {
iterator.nextNode();
}
if (size > 0) {
head = iterator.nextNode();
size = size() - firstSize;
}
}
/**
* 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 (i == 0) {
removeFirstSize(length);
return;
}
if (i >= size || length == 0) {
return;
}
int lastLenth = size - i;
length = length <= lastLenth ? length : lastLenth;
Node pre = node(i - 1);
int j = 0;
Node next = pre;
while (j++ < length) {
next = next.next;
}
pre.next = next.next;
size = size - length;
}
/**
* 假定当前链表和listB均包含已升序排列的整数
* 从当前链表中取出那些listB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 (size() == 0) {
return new int[0];
}
Iterator iterator = list.iterator();
Node fromNode = iterator().nextNode();
int fromIndex = 0;
int[] retArray = new int[list.size()];
int retIndex = 0;
while (iterator.hasNext()) {
int index = (int) iterator.next();
Node node = node(fromNode, fromIndex, index);
fromIndex = index;
fromNode = node;
if (node == null) {
return retArray;
} else {
retArray[retIndex++] = (int)node.data;
}
}
return retArray;
}
private Node node(Node fromNode, int fromIndex, int index) {
Node next = fromNode;
int nextIndex = fromIndex;
while (next != null && nextIndex < index) {
next = next.next;
nextIndex++;
}
if (nextIndex == index) {
return next;
} else {
return null;
}
}
/**
* 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listB中出现的元素
*
* @param list
*/
public void subtract(LinkedList list) {
}
/**
* 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() {
}
/**
* 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) {
}
/**
* 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) {
return null;
}
private static class Node {
Object data;
Node next;
public Node() {
}
public Node(Object data, Node next) {
this.data = data;
this.next = next;
}
}
private class LinkedListIterator implements Iterator {
private Node next;
public LinkedListIterator() {
}
private LinkedListIterator(Node next) {
this.next = next;
}
@Override
public boolean hasNext() {
return next != null;
}
@Override
public Object next() {
if (next == null) {
throw new IndexOutOfBoundsException("there is no node in list");
}
Node ret = next;
next = next.next;
return ret.data;
}
private Node nextNode() {
if (next == null) {
throw new IndexOutOfBoundsException("there is no node in list");
}
Node ret = next;
next = next.next;
return ret;
}
}
}