Java/DataStructures/Lists/SinglyLinkedList.java at master · debugmm/Java · GitHub

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package DataStructures.Lists;

import java.util.StringJoiner;

/** https://en.wikipedia.org/wiki/Linked_list */

public class SinglyLinkedList {

/** Head refer to the front of the list */

private Node head;

/** Size of SinglyLinkedList */

private int size;

/** Init SinglyLinkedList */

public SinglyLinkedList() {

head = null;

size = 0;

}

/**

* Init SinglyLinkedList with specified head node and size

* @param head the head node of list

* @param size the size of list

public SinglyLinkedList(Node head, int size) {

this.head = head;

this.size = size;

}

/**

* Inserts an element at the head of the list

* @param x element to be added

public void insertHead(int x) {

insertNth(x, 0);

}

/**

* Insert an element at the tail of the list

* @param data element to be added

public void insert(int data) {

insertNth(data, size);

}

/**

* Inserts a new node at a specified position of the list

* @param data data to be stored in a new node

* @param position position at which a new node is to be inserted

public void insertNth(int data, int position) {

checkBounds(position, 0, size);

Node newNode = new Node(data);

if (head == null) {

/* the list is empty */

head = newNode;

size++;

return;

} else if (position == 0) {

/* insert at the head of the list */

newNode.next = head;

head = newNode;

size++;

return;

}

Node cur = head;

for (int i = 0; i < position - 1; ++i) {

cur = cur.next;

}

newNode.next = cur.next;

cur.next = newNode;

size++;

}

/** Deletes a node at the head */

public void deleteHead() {

deleteNth(0);

}

/** Deletes an element at the tail */

public void delete() {

deleteNth(size - 1);

}

/** Deletes an element at Nth position */

public void deleteNth(int position) {

checkBounds(position, 0, size - 1);

if (position == 0) {

Node destroy = head;

head = head.next;

destroy = null; /* clear to let GC do its work */

size--;

return;

}

Node cur = head;

for (int i = 0; i < position - 1; ++i) {

cur = cur.next;

}

Node destroy = cur.next;

cur.next = cur.next.next;

destroy = null; // clear to let GC do its work

size--;

}

/**

* @param position to check position

* @param low low index

* @param high high index

* @throws IndexOutOfBoundsException if {@code position} not in range {@code low} to {@code high}

public void checkBounds(int position, int low, int high) {

if (position > high || position < low) {

throw new IndexOutOfBoundsException(position + "");

}

/** Clear all nodes in the list */

public void clear() {

Node cur = head;

while (cur != null) {

Node prev = cur;

cur = cur.next;

prev = null; // clear to let GC do its work

}

head = null;

size = 0;

}

/**

* Checks if the list is empty

* @return {@code true} if list is empty, otherwise {@code false}.

public boolean isEmpty() {

return size == 0;

}

/**

* Returns the size of the linked list.

* @return the size of the list.

public int size() {

return size;

}

/**

* Get head of the list.

* @return head of the list.

public Node getHead() {

return head;

}

/**

* Calculate the count of the list manually

* @return count of the list

public int count() {

int count = 0;

Node cur = head;

while (cur != null) {

cur = cur.next;

count++;

}

return count;

}

/**

* Test if the value key is present in the list.

* @param key the value to be searched.

* @return {@code true} if key is present in the list, otherwise {@code false}.

public boolean search(int key) {

Node cur = head;

while (cur != null) {

if (cur.value == key) {

return true;

}

cur = cur.next;

}

return false;

}

/**

* Return element at special index.

* @param index given index of element

* @return element at special index.

public int getNth(int index) {

checkBounds(index, 0, size - 1);

Node cur = head;

for (int i = 0; i < index; ++i) {

cur = cur.next;

}

return cur.value;

}

@Override

public String toString() {

StringJoiner joiner = new StringJoiner("->");

Node cur = head;

while (cur != null) {

joiner.add(cur.value + "");

cur = cur.next;

}

return joiner.toString();

}

/** Driver Code */

public static void main(String[] arg) {

SinglyLinkedList list = new SinglyLinkedList();

assert list.isEmpty();

assert list.size() == 0 && list.count() == 0;

assert list.toString().equals("");

/* Test insert function */

list.insertHead(5);

list.insertHead(7);

list.insertHead(10);

list.insert(3);

list.insertNth(1, 4);

assert list.toString().equals("10->7->5->3->1");

/* Test search function */

assert list.search(10) && list.search(5) && list.search(1) && !list.search(100);

/* Test get function */

assert list.getNth(0) == 10 && list.getNth(2) == 5 && list.getNth(4) == 1;

/* Test delete function */

list.deleteHead();

list.deleteNth(1);

list.delete();

assert list.toString().equals("7->3");

assert list.size == 2 && list.size() == list.count();

list.clear();

assert list.isEmpty();

try {

list.delete();

assert false; /* this should not happen */

} catch (Exception e) {

assert true; /* this should happen */

}

/**

* This class is the nodes of the SinglyLinked List. They consist of a value and a pointer to the

* node after them.

class Node {

/** The value of the node */

int value;

/** Point to the next node */

Node next;

Node() {}

/**

* Constructor

* @param value Value to be put in the node

Node(int value) {

this(value, null);

}

/**

* Constructor

* @param value Value to be put in the node

* @param next Reference to the next node

Node(int value, Node next) {

this.value = value;

this.next = next;

}

Java/DataStructures/Lists/SinglyLinkedList.java at master · debugmm/Java · GitHub

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