TheAlgorithms · raklaptudirm · Apr 10, 2022 · Feb 16, 2022 · Apr 7, 2022 · Apr 9, 2022
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+// Methods - size, head, isEmpty, getElementAt, addAtFirst, add, clean, insertAt, remove, removeData, printData, get, clear
+import { Node } from './SinglyLinkedList.js'
+
+class SinglyCircularLinkedList {
+  constructor () {
+    this.headNode = null
+    this.length = 0
+  }
+
+  // Get size of the linkedList
+  size = () => this.length
+  // Get the headNode data
+  head = () => this.headNode?.data || null
+  // Check if the linkedList is empty
+  isEmpty = () => this.length === 0
+
+  // initiate the node and index
+  initiateNodeAndIndex () {
+    return { currentNode: this.headNode, currentIndex: 0 }
+  }
+
+  // get the data specific to an index
+  getElementAt (index) {
+    if (this.length !== 0 && index >= 0 && index <= this.length) {
+      let { currentNode } = this.initiateNodeAndIndex()
+      for (let i = 0; i < index && currentNode !== null; i++) {
+        currentNode = currentNode.next
+      }
+      return currentNode
+    }
+    return undefined
+  }
+
+  // Add the element in the first position
+  addAtFirst (data) {
+    const node = new Node(data)
+    node.next = this.headNode
+    this.headNode = node
+    this.length++
+    return this.length
+  }
+
+  // Add any data to the end of the linkedList
+  add (data) {
+    if (!this.headNode) { return this.addAtFirst(data) }
+    const node = new Node(data)
+    // Getting the last node
+    const currentNode = this.getElementAt(this.length - 1)
+    currentNode.next = node
+    node.next = this.headNode
+    this.length++
+    return this.length
+  }
+
+  // insert data at a specific position
+  insertAt (index, data) {
+    if (index === 0) return this.addAtFirst(data)
+    if (index === this.length) return this.add(data)
+    if (index < 0 || index > this.length) throw new RangeError(`Index is out of range max ${this.length}`)
+    const node = new Node(data)
+    const previousNode = this.getElementAt(index - 1)
+    node.next = previousNode.next
+    previousNode.next = node
+    this.length++
+    return this.length
+  }
+
+  // find the first index of the data
+  indexOf (data) {
+    let { currentNode } = this.initiateNodeAndIndex()
+    // initializing currentIndex as -1
+    let currentIndex = -1
+    while (currentNode) {
+      if (currentNode.data === data) {
+        return currentIndex + 1
+      }
+      currentIndex++
+      currentNode = currentNode.next
+    }
+    return -1
+  }
+
+  // remove the data from the end of the list
+  remove () {
+    if (this.isEmpty()) return null
+    const secondLastNode = this.getElementAt(this.length - 2)
+    const removedNode = secondLastNode.next
+    secondLastNode.next = this.headNode
+    this.length--
+    return removedNode.data || null
+  }
+
+  // remove the data from the first of the list
+  removeFirst () {
+    if (this.isEmpty()) return null
+    const removedNode = this.headNode
+    if (this.length === 1) {
+      this.clear()
+      return removedNode.data
+    }
+    const lastNode = this.getElementAt(this.length - 1)
+    this.headNode = this.headNode.next
+    lastNode.next = this.headNode
+    this.length--
+    return removedNode.data || null
+  }
+
+  // remove the data from the index
+  removeAt (index) {
+    if (this.isEmpty()) return null
+    if (index === 0) return this.removeFirst()
+    if (index === this.length) return this.remove()
+    if (index < 0 && index > this.length) return null
+    const previousNode = this.getElementAt(index - 1)
+    const currentNode = previousNode.next
+    previousNode.next = currentNode.next
+    this.length--
+    return currentNode.data || null
+  }
+
+  // remove if the data is present
+  removeData (data) {
+    if (this.isEmpty()) return null
+    const index = this.indexOf(data)
+    return this.removeAt(index)
+  }
+
+  // logs the data
+  printData (output = value => console.log(value)) {
+    let { currentIndex, currentNode } = this.initiateNodeAndIndex()
+
+    while (currentNode !== null && currentIndex < this.length) {
+      output(currentNode.data)
+      currentNode = currentNode.next
+      currentIndex++
+    }
+  }
+
+  // get the data from the linkedList
+  get () {
+    let { currentIndex, currentNode } = this.initiateNodeAndIndex()
+    const list = []
+    while (currentNode !== null && currentIndex < this.length) {
+      list.push(currentNode.data)
+      currentNode = currentNode.next
+      currentIndex++
+    }
+    return list
+  }
+
+  clear () {
+    this.headNode = null
+    this.length = 0
+  }
+}
+
+export { SinglyCircularLinkedList }
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+import { SinglyCircularLinkedList } from '../SinglyCircularLinkedList'
+
+describe('SinglyCircularLinkedList', () => {
+  let list
+  beforeEach(() => {
+    list = new SinglyCircularLinkedList()
+  })
+  it('Check get', () => {
+    expect(list.get()).toEqual([])
+    expect(list.add(1)).toEqual(1)
+    expect(list.get()).toEqual([1])
+    expect(list.add(5)).toEqual(2)
+    expect(list.get()).toEqual([1, 5])
+  })
+
+  it('Check size', () => {
+    expect(list.size()).toEqual(0)
+    expect(list.add(1)).toEqual(1)
+    expect(list.add(1)).toEqual(2)
+    expect(list.size()).toEqual(2)
+  })
+
+  it('Check head', () => {
+    expect(list.head()).toEqual(null)
+    expect(list.add(1)).toEqual(1)
+    expect(list.head()).toEqual(1)
+    expect(list.add(1)).toEqual(2)
+    expect(list.head()).toEqual(1)
+    expect(list.addAtFirst(100)).toEqual(3)
+    expect(list.head()).toEqual(100)
+    expect(list.insertAt(0, 500)).toEqual(4)
+    expect(list.head()).toEqual(500)
+    list.clear()
+    expect(list.head()).toEqual(null)
+  })
+
+  it('Check isEmpty', () => {
+    expect(list.isEmpty()).toEqual(true)
+    expect(list.add(1)).toEqual(1)
+    expect(list.add(1)).toEqual(2)
+    expect(list.isEmpty()).toEqual(false)
+  })
+
+  it('Check getElementAt', () => {
+    list.add(100)
+    list.add(200)
+    list.add(300)
+    list.add(500)
+    list.add(900)
+
+    expect(list.getElementAt(1).data).toEqual(200)
+    expect(list.getElementAt(3).data).toEqual(500)
+  })
+
+  it('Check addAtFirst', () => {
+    list.add(1)
+    list.add(5)
+    list.add(7)
+    list.add(9)
+    list.add(0)
+    expect(list.get()).toEqual([1, 5, 7, 9, 0])
+    list.addAtFirst(100)
+    expect(list.get()).toEqual([100, 1, 5, 7, 9, 0])
+  })
+
+  it('Check add', () => {
+    list.add(1)
+    list.add(5)
+    list.add(7)
+    list.add(9)
+    list.add(0)
+    expect(list.get()).toEqual([1, 5, 7, 9, 0])
+    list.add(100)
+    expect(list.get()).toEqual([1, 5, 7, 9, 0, 100])
+  })
+
+  it('Check insertAt', () => {
+    expect(list.insertAt(0, 100)).toEqual(1)
+    expect(list.get()).toEqual([100])
+    expect(list.insertAt(0, 200)).toEqual(2)
+    expect(list.get()).toEqual([200, 100])
+    expect(list.insertAt(2, 300)).toEqual(3)
+    expect(list.get()).toEqual([200, 100, 300])
+  })
+
+  it('Checks indexOf', () => {
+    expect(list.indexOf(200)).toEqual(-1)
+    list.add(100)
+    list.add(200)
+    list.add(300)
+    list.add(500)
+    list.add(900)
+    expect(list.indexOf(200)).toEqual(1)
+  })
+
+  it('Check remove', () => {
+    expect(list.remove()).toEqual(null)
+    list.add(100)
+    list.add(200)
+    list.add(300)
+    list.add(500)
+    list.add(900)
+    expect(list.get()).toEqual([100, 200, 300, 500, 900])
+    const removedData = list.remove()
+    expect(removedData).toEqual(900)
+    expect(list.get()).toEqual([100, 200, 300, 500])
+  })
+
+  it('Check removeFirst', () => {
+    expect(list.removeFirst()).toEqual(null)
+    list.add(100)
+    list.add(200)
+    list.add(300)
+    list.add(500)
+    list.add(900)
+    expect(list.get()).toEqual([100, 200, 300, 500, 900])
+    const removedData = list.removeFirst()
+    expect(removedData).toEqual(100)
+    expect(list.get()).toEqual([200, 300, 500, 900])
+  })
+
+  it('Check removeAt', () => {
+    expect(list.removeAt(1)).toEqual(null)
+    list.add(100)
+    list.add(200)
+    list.add(300)
+    list.add(500)
+    list.add(900)
+    expect(list.get()).toEqual([100, 200, 300, 500, 900])
+    const removedData = list.removeAt(2)
+    expect(removedData).toEqual(300)
+    expect(list.get()).toEqual([100, 200, 500, 900])
+  })
+
+  it('Check removeData', () => {
+    expect(list.removeData(100)).toEqual(null)
+    list.add(100)
+    list.add(200)
+    list.add(300)
+    list.add(500)
+    list.add(900)
+    expect(list.get()).toEqual([100, 200, 300, 500, 900])
+    const removedData = list.removeData(200)
+    expect(removedData).toEqual(200)
+    expect(list.get()).toEqual([100, 300, 500, 900])
+  })
+})