Merge pull request #19 from iamwill123/add/quick-sort

add quick sort

Author: iamwill123

README.md

@@ -108,3 +108,4 @@ yarn coverage
 
 - [ ] Think about separating each algo into its own page
 - [ ] Add notes and drawings for each algo
+- [ ] Unit the helper functions

src/index.ts

@@ -3,5 +3,13 @@ import nativeSort from './lib/sorts/native'
 import selectionSort from './lib/sorts/selection'
 import insertionSort from './lib/sorts/insertion'
 import mergeSort from './lib/sorts/merge'
+import quickSort from './lib/sorts/quick'
 
-export { nativeSort, bubbleSort, selectionSort, insertionSort, mergeSort }
+export {
+	nativeSort,
+	bubbleSort,
+	selectionSort,
+	insertionSort,
+	mergeSort,
+	quickSort,
+}

src/lib/helpers/index.ts

@@ -1,4 +1,9 @@
-import { ArrayInput, GenerateRandomNumbers, SortOrder } from '../../types/sorts'
+import {
+	ArrayInput,
+	GenerateRandomNumbers,
+	NumberOrObject,
+	SortOrder,
+} from '../../types/sorts'
 
 const startTime = () => Date.now()
 const endTime = () => Date.now()
@@ -28,6 +33,31 @@ const generateRandomNumbers = ({
 const sleep = (ms: number): Promise<void> => {
 	return new Promise((resolve) => setTimeout(resolve, ms))
 }
+
+const pickRandomIndex = (start: number, end: number) =>
+	Math.floor(Math.random() * (end - start + 1) + start)
+
+// compare is a helper function that compares two numbers or two objects by a key and order (asc or desc) and returns a number (-1, 0, or 1) based on the comparison.
+const compare = (
+	a: NumberOrObject,
+	b: NumberOrObject,
+	key: string = '',
+	order: string = 'asc'
+): number => {
+	if (key) {
+		a = a[key]
+		b = b[key]
+	}
+
+	if (isAsc(order)) {
+		return a < b ? -1 : a > b ? 1 : 0
+	} else if (isDesc(order)) {
+		return a > b ? -1 : a < b ? 1 : 0
+	} else {
+		throw new Error(`Invalid order: ${order}.`)
+	}
+}
+
 export {
 	startTime,
 	endTime,
@@ -39,4 +69,6 @@ export {
 	generateRandomNumbers,
 	findMaxNumber,
 	sleep,
+	pickRandomIndex,
+	compare,
 }

src/lib/sorts/insertion/index.ts

@@ -10,6 +10,7 @@
 */
 
 import {
+	compare,
 	endTime,
 	howLongExecTook,
 	isAsc,
@@ -64,25 +65,4 @@ async function insertion(input: SortInput): Promise<SortOutput> {
 	return { arr, key, order, n, execTime: execTimeInMs, animate }
 }
 
-// compare is a helper function that compares two numbers or two objects by a key and order (asc or desc) and returns a number (-1, 0, or 1) based on the comparison.
-function compare(
-	a: NumberOrObject,
-	b: NumberOrObject,
-	key = '',
-	order = 'asc'
-): number {
-	if (key) {
-		a = a[key]
-		b = b[key]
-	}
-
-	if (isAsc(order)) {
-		return a < b ? -1 : a > b ? 1 : 0
-	} else if (isDesc(order)) {
-		return a > b ? -1 : a < b ? 1 : 0
-	} else {
-		throw new Error(`Invalid order: ${order}.`)
-	}
-}
-
 export default insertion

src/lib/sorts/quick/index.ts

@@ -0,0 +1,146 @@
+/*
+quick sort is a divide and conquer algorithm that recursively divides a list into a smaller list and a larger list based on a pivot element. It then sorts the smaller list and the larger list by recursively calling itself. This process continues until the entire list is sorted. Here we are using the Lomuto partition scheme.
+*/
+
+import {
+	compare,
+	endTime,
+	howLongExecTook,
+	isAnObj,
+	pickRandomIndex,
+	startTime,
+} from '../../helpers'
+import { ArrayInput, SortInput, SortOutput } from '../../../types/sorts'
+
+type HelperInput = {
+	arr: ArrayInput
+	startIdx: number
+	endIdx: number
+	partitionType: string
+	order: string
+	key: string
+	callback: Function
+	animate: boolean
+}
+
+async function quick_sort(
+	input: SortInput,
+	partitionType: string = 'lomuto'
+): Promise<SortOutput> {
+	const _s = startTime()
+	const {
+		arr,
+		order = 'asc',
+		key = '',
+		callback = () => {},
+		isSorting = () => true,
+	} = input
+
+	const n: number = arr.length
+	let startIdx: number = 0
+	let endIdx: number = n - 1
+
+	let animate: boolean = false
+
+	if (n <= 0 || !isSorting()) {
+		return { arr, key, order, n, execTime: 0, animate: false }
+	}
+
+	if (isAnObj(0, arr) && !key) throw new Error('key is required')
+
+	// recursive case
+	helper({
+		arr,
+		startIdx,
+		endIdx,
+		partitionType,
+		order,
+		key,
+		callback,
+		animate,
+	})
+
+	const _e = endTime()
+	const execTimeInMs = howLongExecTook(_s, _e)
+
+	return {
+		arr,
+		key,
+		order,
+		n,
+		execTime: execTimeInMs,
+		animate,
+	}
+}
+
+function helper(helperInput: HelperInput) {
+	const {
+		arr,
+		startIdx,
+		endIdx,
+		partitionType,
+		order,
+		key,
+		callback,
+		animate,
+	} = helperInput
+
+	// base case
+	// the leaf workers either 1 or 0
+	if (startIdx >= endIdx) return
+
+	let pivotIdx = pickRandomIndex(startIdx, endIdx)
+	let pivotElem = arr[pivotIdx]
+	// make the pivot value the start of the array
+	;[arr[startIdx], arr[pivotIdx]] = [arr[pivotIdx], arr[startIdx]]
+
+	let smaller = 0,
+		bigger = 0
+
+	if (partitionType === 'hoare') {
+		// hoare's partitioning
+		smaller = startIdx + 1
+		bigger = endIdx
+
+		while (smaller <= bigger) {
+			// compare the next number at "smaller" to the pivot elem at startIdx
+			if (compare(arr[smaller], pivotElem, key, order) <= 0) {
+				smaller++
+			} else if (compare(arr[bigger], pivotElem, key, order) > 0) {
+				bigger--
+			} else {
+				;[arr[smaller], arr[bigger]] = [arr[bigger], arr[smaller]]
+				smaller++
+				bigger--
+			}
+		}
+
+		// put the pivot element to where the smaller index left off after the loop
+		;[arr[startIdx], arr[bigger]] = [arr[bigger], arr[startIdx]]
+
+		// recursive case
+		helper({ ...helperInput, endIdx: bigger }) // include the pivot in the first half
+		helper({ ...helperInput, startIdx: bigger + 1 }) // start from the next element of the pivot
+	}
+
+	if (partitionType === 'lomuto') {
+		// lomuto's partitioning
+		smaller = startIdx
+		bigger = startIdx
+		for (let i = bigger + 1; i <= endIdx; i++) {
+			// compare the next number at "bigger" to the pivot elem at startIdx
+			if (compare(arr[i], pivotElem, key, order) < 0) {
+				smaller++
+				;[arr[smaller], arr[i]] = [arr[i], arr[smaller]]
+			}
+		}
+		// put the pivot element to where the smaller index left off after the loop
+		;[arr[startIdx], arr[smaller]] = [arr[smaller], arr[startIdx]]
+
+		// recursive case
+		helper({ ...helperInput, endIdx: smaller - 1 })
+		helper({ ...helperInput, startIdx: smaller + 1 })
+	}
+}
+
+export default quick_sort

test/sorts/merge/index.test.ts

@@ -24,9 +24,6 @@ describe('merge sort', () => {
 		let order = 'desc'
 		const obj = { arr: unsorted().arr.numbers, order }
 		const { arr: arrOfNums } = await merge(obj)
-		console.log('🚀 ~ file: index.test.ts:27 ~ test ~ obj:', obj)
-
-		console.log('🚀 ~ file: index.test.ts:29 ~ test ~ arrOfNums:', arrOfNums)
 		expect(arrOfNums).toEqual(sorted({ order }).arr.numbers)
 	})
 

test/sorts/quick/index.test.ts

@@ -0,0 +1,104 @@
+import quick from '../../../src/lib/sorts/quick'
+import { cases } from '../test-cases'
+import { testData } from '../test-data'
+
+describe('quick sort', () => {
+	const { unsorted, sorted } = testData
+	test('cases[0]: ' + cases[0], async () => {
+		const obj = { arr: [5] }
+		const { arr: arrOfNums } = await quick(obj)
+		expect(arrOfNums).toEqual([5])
+
+		const obj1 = { arr: [] }
+		const { arr: arrOfNums1 } = await quick(obj1)
+		expect(arrOfNums1).toEqual([])
+	})
+
+	test('cases[1]: ' + cases[1], async () => {
+		const obj = { arr: unsorted().arr.numbers }
+		const { arr: arrOfNums } = await quick(obj)
+		expect(arrOfNums).toEqual(sorted().arr.numbers)
+	})
+
+	test('cases[2]: ' + cases[2], async () => {
+		let order = 'desc'
+		const obj = { arr: unsorted().arr.numbers, order }
+		const { arr: arrOfNums } = await quick(obj)
+		expect(arrOfNums).toEqual(sorted({ order }).arr.numbers)
+	})
+
+	test('cases[3]: ' + cases[3], async () => {
+		const obj = {
+			arr: unsorted().arr.objects,
+			key: 'age',
+		}
+		const { arr: arrOfObjs } = await quick(obj)
+
+		expect(arrOfObjs).toEqual(sorted({}).arr.objects)
+	})
+
+	test('cases[4]: ' + cases[4], async () => {
+		let key = 'height',
+			order = 'desc'
+		const obj = {
+			arr: unsorted({ key }).arr.objects,
+			key,
+			order,
+		}
+		const { arr: arrOfObjs } = await quick(obj)
+		expect(arrOfObjs).toEqual(sorted({ key, order }).arr.objects)
+	})
+
+	test('cases[5]: ' + cases[5], async () => {
+		const obj = {
+			arr: unsorted().arr.numbers,
+			isSorting: () => false,
+		}
+		const { arr: arrOfNums } = await quick(obj)
+		expect(arrOfNums).toEqual(unsorted().arr.numbers)
+	})
+
+	test.todo('cases[6]: ' + cases[6])
+	// test('cases[6]: ' + cases[6], async () => {
+	// 	const obj = {
+	// 		arr: unsorted().arr.numbers,
+	// 		callback: async (a: number, b: number) => {
+	// 			return await Promise.resolve()
+	// 		},
+	// 	}
+	// 	const { arr: arrOfNums, animate } = await quick(obj)
+	// 	expect(arrOfNums).toEqual(sorted().arr.numbers)
+	// 	expect(animate).toEqual(true)
+	// })
+
+	test.todo('cases[7]: ' + cases[7])
+	// test('cases[7]: ' + cases[7], async () => {
+	// 	const obj = {
+	// 		arr: unsorted().arr.numbers,
+	// 		callback: async () => {
+	// 			return await Promise.resolve()
+	// 		},
+	// 	}
+	// 	const { arr: arrOfNums, animate } = await quick(obj)
+	// 	expect(arrOfNums).toEqual(sorted().arr.numbers)
+	// 	expect(animate).toEqual(false)
+	// })
+	test('cases[8]: should sort correctly when switching partition type to "hoare"', async () => {
+		const partitionType = 'hoare'
+		const obj = {
+			arr: unsorted().arr.numbers,
+		}
+		const { arr: arrOfNums } = await quick(obj, partitionType)
+		expect(arrOfNums).toEqual(sorted().arr.numbers)
+
+		let key = 'height',
+			order = 'desc'
+		const obj1 = {
+			arr: unsorted({ key }).arr.objects,
+			key,
+			order,
+		}
+		const { arr: arrOfObjs } = await quick(obj1, partitionType)
+		expect(arrOfObjs).toEqual(sorted({ key, order }).arr.objects)
+	})
+})