Sep 24, 2025
diff --git a/PrefixSum/BasicPrefixSum.js b/PrefixSum/BasicPrefixSum.js
 /**
 * BasicPrefixSum.js
 * Implementation of Prefix Sum array.
 *
 * @param {number[]} arr - Input array of numbers.
 * @returns {number[]} Prefix sum array.
 * @throws {TypeError} If input is not an array of numbers.
 *
 * Explanation:
 * Given [1,2,3,4], returns [1,3,6,10]
 */

 export function basicPrefixSum(arr) {
  // Validate input
  if (!Array.isArray(arr) || arr.some((x) => typeof x !== 'number')) {
    throw new TypeError('Input must be an array of numbers')
  }

  // Handle empty array
  if (arr.length === 0) return []

  const prefix = new Array(arr.length)
  prefix[0] = arr[0]

  for (let i = 1; i < arr.length; i++) {
    prefix[i] = prefix[i - 1] + arr[i]
  }

  return prefix
 }
diff --git a/PrefixSum/BasicPrefixSum.test.js b/PrefixSum/BasicPrefixSum.test.js
 import { describe, it, expect } from 'vitest'
 import { basicPrefixSum } from './BasicPrefixSum.js'

 describe('Basic Prefix Sum', () => {
  it('should compute prefix sum of a normal array', () => {
    const arr = [1, 2, 3, 4]
    const expected = [1, 3, 6, 10]
    expect(basicPrefixSum(arr)).toEqual(expected)
  })

  it('should return empty array for empty input', () => {
    expect(basicPrefixSum([])).toEqual([])
  })

  it('should throw TypeError for non-numeric array', () => {
    expect(() => basicPrefixSum([1, 'a', 3])).toThrow(TypeError)
  })

  it('should handle single element array', () => {
    expect(basicPrefixSum([5])).toEqual([5])
  })

  it('should handle negative numbers', () => {
    expect(basicPrefixSum([-1, -2, -3])).toEqual([-1, -3, -6])
  })
 })
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,30 @@
		/**
		* BasicPrefixSum.js
		* Implementation of Prefix Sum array.
		*
		* @param {number[]} arr - Input array of numbers.
		* @returns {number[]} Prefix sum array.
		* @throws {TypeError} If input is not an array of numbers.
		*
		* Explanation:
		* Given [1,2,3,4], returns [1,3,6,10]
		*/

		export function basicPrefixSum(arr) {
		// Validate input
		if (!Array.isArray(arr) \|\| arr.some((x) => typeof x !== 'number')) {
		throw new TypeError('Input must be an array of numbers')
		}

		// Handle empty array
		if (arr.length === 0) return []

		const prefix = new Array(arr.length)
		prefix[0] = arr[0]

		for (let i = 1; i < arr.length; i++) {
		prefix[i] = prefix[i - 1] + arr[i]
		}

		return prefix
		}
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,26 @@
		import { describe, it, expect } from 'vitest'
		import { basicPrefixSum } from './BasicPrefixSum.js'

		describe('Basic Prefix Sum', () => {
		it('should compute prefix sum of a normal array', () => {
		const arr = [1, 2, 3, 4]
		const expected = [1, 3, 6, 10]
		expect(basicPrefixSum(arr)).toEqual(expected)
		})

		it('should return empty array for empty input', () => {
		expect(basicPrefixSum([])).toEqual([])
		})

		it('should throw TypeError for non-numeric array', () => {
		expect(() => basicPrefixSum([1, 'a', 3])).toThrow(TypeError)
		})

		it('should handle single element array', () => {
		expect(basicPrefixSum([5])).toEqual([5])
		})

		it('should handle negative numbers', () => {
		expect(basicPrefixSum([-1, -2, -3])).toEqual([-1, -3, -6])
		})
		})