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Copy pathMyLinkedList.java
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196 lines (165 loc) · 3.92 KB
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import java.util.NoSuchElementException;
public class MyLinkedList<E> {
final private Node head, tail;
private int size;
private class Node {
private E data;
private Node next;
private Node prev;
public Node(E data) {
this.data = data;
this.next = null;
this.prev = null;
}
}
public MyLinkedList() {
head = new Node(null);
tail = new Node(null);
head.next = tail;
tail.prev = head;
size = 0;
}
private boolean isElementIndex(int index) {
return index >= 0 && index < size;
}
private boolean isPositionIndex(int index) {
return index >= 0 && index <= size;
}
private void checkElementIndex(int index) {
if (!isElementIndex(index)) {
throw new NoSuchElementException("Index: " + index + ", Size: " + size);
}
}
private void checkPositionIndex(int index) {
if (!isPositionIndex(index)) {
throw new NoSuchElementException("Index: " + index + ", Size: " + size);
}
}
public Node getNode(int index) {
checkElementIndex(index);
Node cur = head.next;
for (int i = 0; i < index; i++) {
cur = cur.next;
}
return cur;
}
// addAtIndex an element
public void addAtTail(E e) {
Node newNode = new Node(e);
Node last = tail.prev;
last.next = newNode;
newNode.next = tail;
newNode.prev = last;
tail.prev = newNode;
size++;
}
public void addAtHead(E e) {
Node newNode = new Node(e);
newNode.next = head.next;
newNode.prev = head;
head.next.prev = newNode;
head.next = newNode;
size++;
}
public void addAtIndex(int index, E e) {
checkPositionIndex(index);
Node newNode = new Node(e);
Node cur = getNode(index);
Node curPrev = cur.prev;
newNode.prev = curPrev;
curPrev.next = newNode;
newNode.next = cur;
cur.prev = newNode;
size++;
}
public E deleteAtIndex(int index) {
checkElementIndex(index);
Node deleteNode = getNode(index);
deleteNode.prev.next = deleteNode.next;
deleteNode.next.prev = deleteNode.prev;
size--;
return deleteNode.data;
}
public E removeFirst() {
checkElementIndex(0);
Node delNode = head.next;
Node delNodeNext = delNode.next;
head.next = delNodeNext;
delNodeNext.prev = head;
delNode.next = null;
delNode.prev = null;
size--;
return delNode.data;
}
public E removeLast() {
if (size < 1) {
throw new NoSuchElementException();
}
Node delNode = tail.prev;
Node delNodePrev = delNode.prev;
tail.prev = delNodePrev;
delNodePrev.next = tail;
delNode.prev = null;
delNode.next = null;
size--;
return delNode.data;
}
public E get(int index) {
checkElementIndex(index);
Node cur = getNode(index);
return cur.data;
}
public E getFirst() {
checkElementIndex(0);
return head.next.data;
}
public E getLast() {
if (size < 1) {
throw new NoSuchElementException();
}
return tail.prev.data;
}
/**
*
* @param index
* @param e
* @return oldVal
*/
public E set(int index, E e) {
checkElementIndex(index);
Node cur = getNode(index);
E oldVal = cur.data;
cur.data = e;
return oldVal;
}
public int size() {
return size;
}
public boolean isEmpty() {
return size == 0;
}
private void display() {
System.out.println("size = " + size);
for (Node p = head.next; p != tail; p = p.next) {
System.out.print(p.data + " <-> ");
}
System.out.println("null");
System.out.println();
}
public static void main(String[] args) {
MyLinkedList<Integer> list = new MyLinkedList<>();
list.addAtTail(1);
list.addAtTail(2);
list.addAtTail(3);
list.addAtHead(0);
list.addAtIndex(2, 100);
list.display();
// size = 5
// 0 <-> 1 <-> 100 <-> 2 <-> 3 <-> null
list.removeFirst();
list.deleteAtIndex(2);
list.display();
// size = 3
// 1 <-> 100 <-> 3 <-> null
}
}