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import java.lang.AssertionError;
/*
* Template for a singly- or doubly-linked list of ints.
*/
public class IntLinkedList {
class Node {
int data;
Node next;
Node(int data) {
this.data = data;
this.next = null;
}
}
int size;
Node head;
Node tail;
/**
* Construct an IntLinkedList.
*/
public IntLinkedList() {
this.head = null;
this.tail = null;
this.size = 0;
}
/**
* Return the number of elements in the IntLinkedList.
*
* @return The number of elements in the IntLinkedList.
*/
public int size() {
return this.size;
}
/**
* Add an element to the end of the IntLinkedList.
*
* @param element The element to add.
*/
public void add(int element) {
if (this.head == null) { // Empty list
this.size++;
this.head = new Node(element);
this.tail = this.head;
} else {
this.size++;
this.tail.next = new Node(element);
this.tail = this.tail.next;
}
}
/**
* Get the element at the specified index.
*
* This function assumes that the index argument is within range of the IntLinkedList.
*
* @param index The index to get.
* @return The element at the specified index.
*/
public int get(int index) {
Node currentNode = this.head;
for (int i = 1; i <= index; i++) {
currentNode = currentNode.next;
}
return currentNode.data;
}
/**
* Remove the element at the specified index.
*
* This function assumes that the index argument is within range of the IntLinkedList.
*
* @param index The index to remove.
*/
public void remove(int index) {
Node currentNode = this.head;
Node previousNode = this.head;
if (index == 0) { // Special case for removing an element at the start of the list
this.head = this.head.next;
}
for (int i = 1; i <= index; i++) {
previousNode = currentNode;
currentNode = previousNode.next;
}
if (currentNode.next == null) { // Special case for removing an element at the end of the list
this.tail = previousNode;
} else {
previousNode.next = currentNode.next;
}
this.size--;
}
/**
* Create a String representation of the IntLinkedList.
*
* @return A String representation of the IntLinkedList.
*/
public String toString() {
String result = "{";
if (this.size() > 0) {
result += this.get(0);
}
for (int i = 1; i < this.size; i++) {
result += ", " + this.get(i);
}
result += "}";
return result;
}
/**
* Check that an IntLinkedList contains the same elements as an int array.
*
* If the list and the array are not the same, throw an AssertionError.
*
* @param list The IntLinkedList to check.
* @param answer The expected answer, in the form of an int array.
*/
public static void assertArraysEqual(IntLinkedList list, int[] answer) {
if (list.size() != answer.length) {
throw new AssertionError("Expected list of length " + answer.length + " but got " + list.size());
}
for (int i = 0; i < answer.length; i++) {
if (list.get(i) != answer[i]) {
throw new AssertionError("Expected " + answer[i] + " but got " + list.get(i) + " at index " + i);
}
}
}
/*
* Test that the empty arraylist has size 0.
*/
public static void test1() {
IntLinkedList list = new IntLinkedList();
int[] answer = new int[0];
assertArraysEqual(list, answer);
}
/*
* Test insertion into an arraylist (without resizing).
*/
public static void test2() {
IntLinkedList list = new IntLinkedList();
for (int i = 0; i < 3; i++) {
list.add(i * i);
}
int[] answer = {0, 1, 4};
assertArraysEqual(list, answer);
}
/*
* Test deletion from an arraylist without emptying it.
*/
public static void test3() {
IntLinkedList list = new IntLinkedList();
for (int i = 0; i < 5; i++) {
list.add(i * i);
}
list.remove(1);
list.remove(2);
int[] answer = {0, 4, 16};
IntLinkedList.assertArraysEqual(list, answer);
}
/*
* Test deletion from an arraylist and emptying it.
*/
public static void test4() {
IntLinkedList list = new IntLinkedList();
for (int i = 0; i < 5; i++) {
list.add(i * i);
}
list.remove(1);
list.remove(2);
// delete the final remaining numbers
list.remove(0);
list.remove(0);
list.remove(0);
int[] answer1 = {};
IntLinkedList.assertArraysEqual(list, answer1);
// check that there are no last-element issues
for (int i = 0; i < 5; i++) {
list.add(i * i);
}
list.remove(4);
list.add(-1);
int[] answer2 = {0, 1, 4, 9, -1};
IntLinkedList.assertArraysEqual(list, answer2);
}
/*
* Test insertion into an arraylist (with resizing).
*/
public static void test5() {
IntLinkedList list = new IntLinkedList();
for (int i = 0; i < 12; i++) {
list.add(i * i);
}
int[] answer = {0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121};
IntLinkedList.assertArraysEqual(list, answer);
}
/**
* Put the IntLinkedList through some simple tests.
*
* @param args Ignored command line arguments.
*/
public static void main(String[] args) {
test1();
test2();
test3();
test4();
test5();
System.out.println("pass");
}
}