Enhance docs, add tests in CircleLinkedList (#5991)

This commit is contained in:
Hardik Pawar
2024-10-25 20:46:34 +05:30
committed by GitHub
parent c766c5e812
commit 202879aa58
2 changed files with 114 additions and 46 deletions

View File

@ -1,8 +1,23 @@
package com.thealgorithms.datastructures.lists;
/**
* This class is a circular singly linked list implementation. In a circular linked list,
* the last node points back to the first node, creating a circular chain.
*
* <p>This implementation includes basic operations such as appending elements
* to the end, removing elements from a specified position, and converting
* the list to a string representation.
*
* @param <E> the type of elements held in this list
*/
public class CircleLinkedList<E> {
private static final class Node<E> {
/**
* A static nested class representing a node in the circular linked list.
*
* @param <E> the type of element stored in the node
*/
static final class Node<E> {
Node<E> next;
E value;
@ -13,44 +28,56 @@ public class CircleLinkedList<E> {
}
}
// For better O.O design this should be private allows for better black box design
private int size;
// this will point to dummy node;
private Node<E> head = null;
private Node<E> tail = null; // keeping a tail pointer to keep track of the end of list
Node<E> head = null;
private Node<E> tail;
// constructor for class.. here we will make a dummy node for circly linked list implementation
// with reduced error catching as our list will never be empty;
/**
* Initializes a new circular linked list. A dummy head node is used for simplicity,
* pointing initially to itself to ensure the list is never empty.
*/
public CircleLinkedList() {
// creation of the dummy node
head = new Node<E>(null, head);
head = new Node<>(null, head);
tail = head;
size = 0;
}
// getter for the size... needed because size is private.
/**
* Returns the current size of the list.
*
* @return the number of elements in the list
*/
public int getSize() {
return size;
}
// for the sake of simplistiy this class will only contain the append function or addLast other
// add functions can be implemented however this is the basses of them all really.
/**
* Appends a new element to the end of the list. Throws a NullPointerException if
* a null value is provided.
*
* @param value the value to append to the list
* @throws NullPointerException if the value is null
*/
public void append(E value) {
if (value == null) {
// we do not want to add null elements to the list.
throw new NullPointerException("Cannot add null element to the list");
}
// head.next points to the last element;
if (tail == null) {
tail = new Node<E>(value, head);
tail = new Node<>(value, head);
head.next = tail;
} else {
tail.next = new Node<E>(value, head);
tail.next = new Node<>(value, head);
tail = tail.next;
}
size++;
}
/**
* Returns a string representation of the list in the format "[ element1, element2, ... ]".
* An empty list is represented as "[]".
*
* @return the string representation of the list
*/
public String toString() {
if (size == 0) {
return "[]";
@ -68,23 +95,27 @@ public class CircleLinkedList<E> {
return sb.toString();
}
/**
* Removes and returns the element at the specified position in the list.
* Throws an IndexOutOfBoundsException if the position is invalid.
*
* @param pos the position of the element to remove
* @return the value of the removed element
* @throws IndexOutOfBoundsException if the position is out of range
*/
public E remove(int pos) {
if (pos >= size || pos < 0) {
// catching errors
throw new IndexOutOfBoundsException("position cannot be greater than size or negative");
throw new IndexOutOfBoundsException("Position out of bounds");
}
// we need to keep track of the element before the element we want to remove we can see why
// bellow.
Node<E> before = head;
for (int i = 1; i <= pos; i++) {
before = before.next;
}
Node<E> destroy = before.next;
E saved = destroy.value;
// assigning the next reference to the element following the element we want to remove...
// the last element will be assigned to the head.
before.next = before.next.next;
// scrubbing
before.next = destroy.next;
if (destroy == tail) {
tail = before;
}