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Copy pathGenericLinkedList.java
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220 lines (198 loc) · 5.17 KB
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public class GenericLinkedList<T> {
int size;
Node head;
Node tail;
public class Node {
T val;
Node next;
Node(T data) { // Node inherits T from GenericLinkedList
this.val = data;
}
}
/** Construct an GenericLinkedList. */
public GenericLinkedList() {}
/**
* Return the number of elements in the GenericLinkedList.
*
* @return The number of elements in the GenericLinkedList.
*/
public int size() {
return this.size;
}
/**
* Add an element to the end of the GenericLinkedList.
*
* @param element The element to add.
*/
public void add(T element) {
this.size++;
Node newNode = new Node(element);
if (this.head == null) {
this.head = newNode;
this.tail = newNode;
return;
}
this.tail.next = newNode;
this.tail = newNode;
}
/**
* Get the element at the specified index.
*
* <p>This function assumes that the index argument is within range of the GenericLinkedList.
*
* @param index The index to get.
* @return The element at the specified index.
*/
public T get(int index) {
Node curNode = this.head;
for (int i = 0; i < this.size; i++) {
if (i == index) {
return curNode.val;
}
curNode = curNode.next;
}
return null;
}
/**
* Remove the element at the specified index.
*
* <p>This function assumes that the index argument is within range of the GenericLinkedList.
*
* @param index The index to remove.
*/
public void remove(int index) {
Node curNode = this.head;
this.size--;
if (index == 0) {
this.head = this.head.next;
return;
}
for (int i = 0; i < index - 1; i++) {
curNode = curNode.next;
}
// Tail
if (curNode.next.next == null) {
this.tail = curNode;
curNode.next = null;
} else {
curNode.next = curNode.next.next;
}
}
/**
* Create a String representation of the GenericLinkedList.
*
* @return A String representation of the GenericLinkedList.
*/
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 GenericLinkedList contains the same elements as an int array.
*
* <p>If the list and the array are not the same, throw an AssertionError.
*
* @param list The GenericLinkedList to check.
* @param answer The expected answer, in the form of an int array.
*/
public static void assertArraysEqual(GenericLinkedList 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 ((Integer) 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() {
GenericLinkedList<Integer> list = new GenericLinkedList<>();
int[] answer = new int[0];
assertArraysEqual(list, answer);
}
/*
* Test insertion into an arraylist (without resizing).
*/
public static void test2() {
GenericLinkedList<Integer> list = new GenericLinkedList<>();
for (int i = 0; i < 3; i++) {
list.add((Integer) i * i);
}
int[] answer = {0, 1, 4};
assertArraysEqual(list, answer);
}
/*
* Test deletion from an arraylist without emptying it.
*/
public static void test3() {
GenericLinkedList<Integer> list = new GenericLinkedList<>();
for (int i = 0; i < 5; i++) {
list.add(i * i);
}
list.remove(1);
list.remove(2);
int[] answer = {0, 4, 16};
GenericLinkedList.assertArraysEqual(list, answer);
}
/*
* Test deletion from an arraylist and emptying it.
*/
public static void test4() {
GenericLinkedList<Integer> list = new GenericLinkedList<>();
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 = {};
GenericLinkedList.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};
GenericLinkedList.assertArraysEqual(list, answer2);
}
/*
* Test insertion into an arraylist (with resizing).
*/
public static void test5() {
GenericLinkedList<Integer> list = new GenericLinkedList<>();
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};
GenericLinkedList.assertArraysEqual(list, answer);
}
/**
* Put the GenericLinkedList 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");
}
}