package task3.linkedlist;
import java.util.Iterator;
public class MyLinkedList<T extends Comparable<T>> {
//存放的元素数量
private int size;
private Node<T> head;
public MyLinkedList() {
head = new Node<>(null, null);
}
public void add(T o) {
add(size, o);
}
public void add(int index, T o) {
if (index < 0 || index > size)
throw new IndexOutOfBoundsException("index " + index + " 不合法");
Node<T> targetNode = new Node<>(null, o);
Node<T> targetPrevNode = getPrevNode(index);
targetNode.next = targetPrevNode.next;
targetPrevNode.next = targetNode;
size++;
}
public T get(int index) {
checkIndexRange(index);
return getPrevNode(index).next.data;
}
public Node<T> getNode(int index) {
checkIndexRange(index);
return getPrevNode(index).next;
}
public T remove(int index) {
checkIndexRange(index);
Node<T> prevNode = getPrevNode(index);
Node<T> nodeToRemove = prevNode.next;
prevNode.next = nodeToRemove.next;
size--;
return nodeToRemove.data;
}
public int size() {
return size;
}
public void addFirst(T o) {
add(0, o);
}
public void addLast(T o) {
add(size, o);
}
public T removeFirst() {
return remove(0);
}
public T removeLast() {
return remove(size - 1);
}
public Iterator<T> iterator() {
return new MyLinkedItr();
}
/**
* 找到位置为index的前一个node
*
* @param index 索引值
*/
private Node<T> getPrevNode(int index) {
Node<T> targetPrevNode = head;
for (int i = 0; i < index; i++) {
targetPrevNode = targetPrevNode.next;
}
return targetPrevNode;
}
/**
* 检查索引是否越界
*
* @param index 索引值
*/
private void checkIndexRange(int index) {
if (index < 0 || index >= size)
throw new IndexOutOfBoundsException("index " + index + " 越界");
}
private static class Node<T> {
private Node<T> next;
private T data;
private Node(Node<T> next, T data) {
this.next = next;
this.data = data;
}
}
private class MyLinkedItr implements Iterator<T> {
private Node<T> currentNode = head;
@Override
public boolean hasNext() {
return currentNode.next != null;
}
@Override
public T next() {
Node<T> nextNode = currentNode.next;
T data = nextNode.data;
currentNode = nextNode;
return data;
}
@Override
public void remove() {
currentNode.next = currentNode.next.next;
}
}
@Override
public String toString() {
if (size == 0)
return "[]";
StringBuilder sb = new StringBuilder();
for (int i = 0; i < size; i++) {
sb.append(get(i)).append(",");
}
return sb.substring(0, sb.length() - 1);
}
/**
* ==================================
* 3.12作业
* ==================================
* <p>
* 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;
int length = size;
for (int i = length - 1; i >= 0; i--) {
add(get(i));
}
remove(0, length); // :(
}
/**
* 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() {
remove(0, size / 2);
}
/**
* 从第i个元素开始， 删除length 个元素 ， 注意i从0开始
*/
public void remove(int i, int length) {
if (length == 0)
return;
if (i + length > size)
throw new IndexOutOfBoundsException("长度不够");
Node<T> startNode = getPrevNode(i);
startNode.next = (i + length == size) ? null : getNode(i + length);
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]
*/
@SuppressWarnings("unchecked")
public T[] getElements(MyLinkedList<Integer> list) {
int size = list.size();
Comparable[] result = new Comparable[size];
int count = 0;
for (int i = 0; i < size; i++) {
result[count++] = get(list.get(i));
}
return (T[]) result;
}
/**
* 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
*/
public void subtract(MyLinkedList list) {
int length = list.size();
for (int i = 0; i < length; i++) {
for (int j = 0; j < size; j++) {
if (get(j).equals(list.get(i))) {
remove(j);
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() {
Iterator<T> iterator = iterator();
int pos = 0;
while (iterator.hasNext()) {
//当前索引的值等于下一个索引的值时,就把当前索引删掉
if (get(pos).equals(get(pos + 1))) {
remove(pos);
}
pos++;
iterator.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）
*/
public void removeRange(T min, T max) {
if (min.compareTo(max) >= 0)
throw new RuntimeException("Are you kidding me ?");
int minIndex = 0;
int maxIndex = size;
for (int i = 0; i < size; i++) {
if (get(i).compareTo(min) > 0) {
minIndex = i;
break;
}
}
for (int i = size - 1; i >= 0; i--) {
if (get(i).compareTo(max) < 0) {
maxIndex = i;
break;
}
}
remove(minIndex, maxIndex - minIndex + 1);
}
/**
* 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
*/
public MyLinkedList intersection(MyLinkedList<T> list) {
MyLinkedList<T> resultList = new MyLinkedList<>();
int firstLength = size;
int secondLength = list.size();
int firstPos = 0;
int secondPos = 0;
while (firstPos < firstLength && secondPos < secondLength) {
T firstItem = get(firstPos);
T secondItem = list.get(secondPos);
int compareResult = firstItem.compareTo(secondItem);
if (compareResult == 0) {
resultList.add(firstItem);
firstPos++;
secondPos++;
} else if (compareResult < 0)
firstPos++;
else
secondPos++;
}
return resultList;
}
}