package datastructure.linkedlist;
import java.util.NoSuchElementException;
import datastructure.Iterator;
import datastructure.List;
public class LinkedList implements List {
private Node head;
private int size = 0;
@Override
public void add(Object o) {
if (head == null) {
head = new Node(o);
} else {
Node tail = head;
while (tail.next != null) {
tail = tail.next;
}
Node node = new Node(o);
tail.next = node;
}
size++;
}
@Override
public void add(int index, Object o) {
rangeCheckForAdd(index);
if (index == 0) {
Node node = new Node(o);
node.next = head;
head = node;
} else {
Node preDest = head;
for (int i = 0; i < index - 1; i++) {
preDest = preDest.next;
}
Node node = new Node(o);
node.next = preDest.next;
preDest.next = node;
}
size++;
}
private void rangeCheckForAdd(int index) {
if (index > size || index < 0) {
throw new IndexOutOfBoundsException();
}
}
@Override
public Object get(int index) {
rangeCheck(index);
Node dest = head;
for (int i = 0; i < index; i++) {
dest = dest.next;
}
return dest.data;
}
private void rangeCheck(int index) {
if (index >= size || index < 0) {
throw new IndexOutOfBoundsException();
}
}
@Override
public Object remove(int index) {
rangeCheck(index);
Node preDest = head;
for (int i = 0; i < index - 1; i++) {
preDest = preDest.next;
}
Node dest = preDest.next;
preDest.next = dest.next;
size--;
return dest.data;
}
@Override
public int size() {
return size;
}
public void addFirst(Object o) {
Node node = new Node(o);
node.next = head;
head = node;
size++;
}
public void addLast(Object o) {
Node lastNode = head;
while (lastNode.next != null) {
lastNode = lastNode.next;
}
Node node = new Node(o);
lastNode.next = node;
size++;
}
public Object removeFirst() {
if (head == null) {
throw new NoSuchElementException();
}
Node target = head;
head = head.next;
size--;
return target.data;
}
public Object removeLast() {
if (head == null) {
throw new NoSuchElementException();
}
Node preDest = head;
while (preDest.next.next != null) {
preDest = preDest.next;
}
Node dest = preDest.next;
preDest.next = null;
size--;
return dest.data;
}
public Iterator iterator() {
return null;
}
private static class Node {
Object data;
Node next;
Node(Object data) {
this.data = data;
next = null;
}
}
// =========================第三周作业=========================
/**
* 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 reverseNode = null;
while (head != null) {
Node temp = head;
head = head.next;
temp.next = reverseNode;
reverseNode = temp;
}
head = reverseNode;
}
/**
* 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() {
int newStartIndex = size / 2;
for (int i = 0; i < newStartIndex; i++) {
head = head.next;
}
size = size - newStartIndex;
}
/**
* 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) {
throw new IllegalArgumentException();
}
if (i + length >= size) {
length = size - i;
}
if (i == 0) {
for (int j = 0; j < length; j++) {
head = head.next;
}
} else {
Node beforeRemoveStartNode = head;
for (int j = 0; j < i - 1; j++) {
beforeRemoveStartNode = beforeRemoveStartNode.next;
}
Node removeEndNode = beforeRemoveStartNode;
for (int j = 0; j < length; j++) {
removeEndNode = removeEndNode.next;
}
beforeRemoveStartNode.next = removeEndNode.next;
}
size = size - length;
}
/**
* 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) {
checkList(list);
int[] dest = new int[list.size];
int arrayNum = 0;
Node temp = head;
int n = (int) list.get(0);
for (int i = 0; i < n; i++) {
temp = temp.next;
}
dest[arrayNum++] = (int) temp.data;
for (int i = 1; i < list.size; i++) {
int num = (int) list.get(i) - (int) list.get(i - 1);
for (int j = 0; j < num; j++) {
temp = temp.next;
}
dest[arrayNum++] = (int) temp.data;
}
return dest;
}
private void checkList(LinkedList list) {
for (int i = 0; i < list.size; i++) {
if ((int) list.get(i) < 0 || (int) list.get(i) >= size) {
throw new IllegalArgumentException("list中的元素位置越界");
}
}
}
/**
* 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) {
if (list == null || list.size == 0 || this.size == 0) {
return;
}
int thisIndex = 0;
int listIndex = 0;
Node temp = head;
while (true) { // 后续需要优化替换remove()方法
if ((int) temp.data < (int) list.get(listIndex)) {
temp = temp.next;
thisIndex++;
} else if ((int) temp.data == (int) list.get(listIndex)) {
this.remove(thisIndex);
temp = temp.next;
thisIndex++;
listIndex++;
} else {
listIndex++;
}
if (thisIndex >= this.size || listIndex >= list.size) {
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() {
if (this.size == 0) {
return;
}
Node subHead = head;
Node subTail = head;
while (true) {
if (subTail == null) {
subHead.next = null; // 清除尾部重复的元素
break;
}
if ((int) subTail.data == (int) subHead.data) {
if (!(subTail == subHead)) { // 判断两个指针是否指向同一个地方
this.size--;
}
subTail = subTail.next;
} else {
subHead.next = subTail;
subHead = subHead.next;
}
}
}
/**
* 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) {
if (this.size == 0) {
return;
}
if ((int) head.data > max) {
throw new IllegalArgumentException();
}
int length = 0;
Node subList = new Node(null);
Node temp = subList;
while (true) {
if (head == null) {
break;
}
if ((int) head.data <= min || (int) head.data >= max) {
temp.next = head;
temp = temp.next;
length++;
}
head = head.next;
}
temp.next = null; // 去掉尾部多余数据
head = subList.next;
size = length;
}
/**
* 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) {
if (this.size == 0 || list.size == 0) {
return null;
}
Node tempHead = head;
int listIndex = 0;
LinkedList newList = new LinkedList();
while (true) {
if (tempHead == null || listIndex >= list.size) {
break;
}
if ((int) tempHead.data < (int) list.get(listIndex)) {
tempHead = tempHead.next;
} else if ((int) tempHead.data > (int) list.get(listIndex)) {
listIndex++;
} else {
newList.add(tempHead.data);
tempHead = tempHead.next;
listIndex++;
}
}
return newList;
}
}