Added Singly linked list

RashikAnsar · RashikAnsar · commit d8ceb1154ba1 · 2018-10-24T10:10:14.000+05:30
diff --git a/data-structures/singlyLinkedList.js b/data-structures/singlyLinkedList.js
@@ -0,0 +1,233 @@
+/**
+ * @author Rashik Ansar
+ *
+ * Implementation of singly linked list
+ * Singly linked list is a linear data strucutre
+ */
+
+class Node {
+  constructor(data) {
+    this.data = data;
+    this.next = null;
+  }
+}
+
+class SinglyLinkedList {
+  constructor() {
+    this.head = null;
+    this.tail = null;
+    this.length = 0;
+  }
+
+  /**
+   * Adding new node as a tail of the linked list
+   * @param {any} data This dataue is added at the end of list
+   * @returns {SinglyLinkedList} LinkedList after adding new node as tail
+   */
+  push(data) {
+    let temp = new Node(data);
+    if (!this.head) {
+      this.head = temp;
+      this.tail = this.head; // temp
+    } else {
+      this.tail.next = temp;
+      this.tail = temp;
+    }
+    this.length++;
+    return this;
+  }
+
+  /**
+   * Adding new node as a head of the linked list
+   * @param {any} data This dataue is added at the beginning of the list
+   * @returns {SinglyLinkedList} LinkedList after adding a new node as head
+   */
+  unshift(data) {
+    let temp = new Node(data);
+    if (!this.head) {
+      this.head = temp;
+      this.tail = this.head;
+    } else {
+      temp.next = this.head;
+      this.head = temp;
+    }
+    this.length++;
+    return this;
+  }
+
+  /**
+   * Adding a node to the linkedList at specified position
+   * @param {number} index Position at which new node to insert
+   * @param {any} data  dataue in the new node
+   * @returns {SinglyLinkedList} LinkedList after inserting a new node
+   */
+  insert(index, data) {
+    if (index < 0 || index > this.length) {
+      throw Error('Given index is out of range');
+    }
+    if (index === this.length) {
+      return this.push(data);
+    }
+    if (index === 0) {
+      return this.unshift(data);
+    }
+    let insertNode = new Node(data);
+    let previous = this.get(index - 1);
+    let temp = previous.next;
+    previous.next = insertNode;
+    insertNode.next = temp;
+    this.length++;
+    return this;
+  }
+
+  /**
+   * Removes the node at the end of linked list(tail of linked list)
+   * @returns {Node} the node which is going to pop
+   */
+  pop() {
+    if (!this.head) {
+      throw Error(
+        'UNDERFLOW :::: LinkedList is empty, there is nothing to remove'
+      );
+    }
+    let current = this.head;
+    let temp = current;
+    while (current.next) {
+      temp = current;
+      current = current.next;
+    }
+    this.tail = temp;
+    this.tail.next = null;
+    this.length--;
+    this.emptyListCheck();
+    return current;
+  }
+
+  /**
+   * Removes the node from the beginnig of linked list(head of linked list)
+   * @returns {Node} the node which is going to shift
+   */
+  shift() {
+    if (!this.head) {
+      throw Error(
+        'UNDERFLOW :::: LinkedList is empty, there is nothing to remove'
+      );
+    }
+    let current = this.head;
+    this.head = current.next;
+    this.length--;
+    this.emptyListCheck();
+    return current;
+  }
+
+  /**
+   * Removes a node from the linkedList at specified position
+   * @param {number} index
+   * @returns {Node} Node which is removed from LinkedList
+   */
+  remove(index) {
+    if (index < 0 || index > this.length) {
+      throw Error('Given index is out of range');
+    }
+    if (index === this.length - 1) {
+      return this.pop();
+    }
+    if (index === 0) {
+      return this.shift();
+    }
+    let previous = this.get(index - 1);
+    let temp = previous.next;
+    previous.next = temp.next;
+    this.length--;
+    return temp;
+  }
+
+  /**
+   * Retrieve the node at specified index
+   * @param {number} index Index of the node
+   * @returns {Node} LinkedList Node at specified index
+   */
+  get(index) {
+    if (index < 0 || index >= this.length) {
+      throw Error('Given index is out of range');
+    }
+    let counter = 0;
+    let current = this.head;
+    while (counter !== index) {
+      current = current.next;
+      counter++;
+    }
+    return current;
+  }
+
+  /**
+   * Change the data of node at specified index
+   * @param {number} index Index of the node
+   * @param {any} data data replaces the current data at given index
+   * @returns {SinglyLinkedList} LinkedList
+   */
+  set(index, data) {
+    // Here error checking will be done by the get method itself
+    // No need to specify explicitly
+    let existedNode = this.get(index);
+    if (existedNode) {
+      existedNode.data = data;
+      return this;
+    }
+  }
+
+  /**
+   * Reversing the Linked list
+   * @returns {SinglyLinkedList} LinkedList
+   */
+  reverse() {
+    let temp = this.head;
+    this.head = this.tail;
+    this.tail = temp;
+
+    let previous = null;
+    let after = null;
+    while (temp) {
+      after = temp.next;
+      temp.next = previous;
+      previous = temp;
+      temp = after;
+    }
+    return this;
+  }
+
+  /**
+   * Traversing or Printing the Linked list
+   */
+  traverse() {
+    let current = this.head;
+    while (current) {
+      console.log(current.data);
+      current = current.next;
+    }
+  }
+
+  /**
+   * @returns {[]} Linkedlist data as elements in Array
+   */
+  listAsArray() {
+    let arr = [];
+    let current = this.head;
+    while (current) {
+      arr.push(current.data);
+      current = current.next;
+    }
+    return arr;
+  }
+
+  /**
+   * Utility Function (PRIVATE FUNCTION)
+   * if the length is zero then assign null to both head and tail
+   */
+  emptyListCheck() {
+    if (this.length === 0) {
+      this.head = null;
+      this.tail = null;
+    }
+  }
+}
