Animal shelter

javascript/code-challenges/animal-shelter/README.md

@@ -0,0 +1,38 @@
+# Challenge Summary
+
+## AnimalShelter 
+- Create a class called AnimalShelter which holds only dogs and cats.
+- The shelter operates using a first-in, first-out approach.
+- 
+
+### Required Methods
+#### `enqueue`
+
+- Arguments: animal
+- animal can be either a dog or a cat object
+
+#### `dequeue`
+
+- Arguments: pref
+- pref can be either "dog" or "cat"
+- Return: either a dog or a cat, based on preference.
+- If pref is not "dog" or "cat" then return null.
+
+## Approach & Efficiency
+
+Use an object for storage
+
+| Method  | Time Complexity | Space Complexity |
+| ---- | ---- | ---- |
+| enqueue | O(1) | O(1)|
+| dequeue | O(n) | O(1) |
+
+
+```Bash
+# run all related tests
+npm test animal-shelter.test.js
+```
+
+### Sources
+
+[ Implement a Queue in JavaScript ](https://initjs.org/implement-a-queue-in-javascript-de306a8821c)

javascript/code-challenges/animal-shelter/animal-shelter.js

@@ -0,0 +1,43 @@
+'use strict'
+
+class AnimalShelter{
+  constructor(storage = {}, front = 0, back = 0) {
+    this.storage = storage
+    this.front = front
+    this.back = back
+  }
+
+  // enqueue
+  enqueue(animalObject) {
+    this.back++
+    this.storage[this.back] = animalObject
+  }
+
+  // dequeue
+  dequeue(pref = null) {
+    if(this.back === 0){throw new Error('Shelter is empty')}
+    let result
+    if(pref === null) {
+      result = this.storage[this.front]
+      delete this.storage[this.front]
+      this.front++
+      return result
+    }
+    let tempCounter = +this.front
+    while(this.storage[`${tempCounter}`].type !== pref && tempCounter < this.back) {
+      let gapCounter = 1
+      while(this.storage[`${tempCounter + gapCounter}`] === undefined && gapCounter < this.back) {
+        gapCounter++
+      }
+      tempCounter+= gapCounter
+    }
+    result = this.storage[`${tempCounter}`]
+    delete this.storage[tempCounter]
+    if(tempCounter === this.front) {
+      this.front++
+    }
+    return result
+  }
+}
+
+module.exports = AnimalShelter

javascript/code-challenges/animal-shelter/animal-shelter.test.js

@@ -0,0 +1,72 @@
+'use strict'
+
+const AnimalShelter = require('./animal-shelter')
+
+let populatedAnimalShelter, emptyAnimalShelter
+
+beforeEach(() => {
+  populatedAnimalShelter = new AnimalShelter({
+    2: {
+      type: 'dog',
+      name: 'Fluff'
+    },
+    4: {
+      type: 'cat',
+      name: 'Mittens'
+    }, 
+    5: {
+      type: 'dog',
+      name: 'Boscow'
+    }
+  }, 2, 5)
+  emptyAnimalShelter = new AnimalShelter()
+})
+
+describe('Given Animal Shelter', () => {
+  describe('When enqueue', () => {
+    let animalToAdd = {
+      type: 'cat',
+      name: 'Smittens'
+    }
+    it('Then should be able to add an animal populated shelter', () => {
+      populatedAnimalShelter.enqueue(animalToAdd)
+      expect(populatedAnimalShelter.storage).toStrictEqual({
+        '2': { type: 'dog', name: 'Fluff' },
+        '4': { type: 'cat', name: 'Mittens' },
+        '5': { type: 'dog', name: 'Boscow' },
+        '6': { type: 'cat', name: 'Smittens' }
+      })
+    })
+
+    it('Then should be able to add animal to empty shelter', () => {
+      emptyAnimalShelter.enqueue(animalToAdd)
+      expect(emptyAnimalShelter.storage).toStrictEqual({
+        '1': { type: 'cat', name: 'Smittens' }
+      })
+    })
+  })
+
+  describe('When dequeue', () => {
+    it('Then should be able to dequeue animal based on preference', () => {
+      populatedAnimalShelter.dequeue('cat')
+      expect(populatedAnimalShelter.storage).toStrictEqual({
+        '2': { type: 'dog', name: 'Fluff' },
+        '5': { type: 'dog', name: 'Boscow' },
+      })
+    })
+
+    it('Then should dequeue animal there the longest if no preference provided', () =>{ 
+      populatedAnimalShelter.dequeue()
+      expect(populatedAnimalShelter.storage).toStrictEqual(
+        {
+          '4': { type: 'cat', name: 'Mittens' }, 
+          '5': { type: 'dog', name: 'Boscow' }
+        }
+      )
+    })
+
+    it('Then should throw error on empty shelter', () => {
+      expect(() => {emptyAnimalShelter.dequeue()}).toThrow('Shelter is empty')
+    })
+  })
+})