From a92fe310984c36a7c83c1f6448306e6e0593fc10 Mon Sep 17 00:00:00 2001
From: Karan Upadhyay <karanupd12@gmail.com>
Date: Sun, 10 Aug 2025 00:57:05 +0530
Subject: [PATCH] all files formatted successfully

---
 PrefixSum/BasicPrefixSum.js      | 37 ++++++++++++++++++++++++++++
 PrefixSum/BasicPrefixSum.test.js | 42 ++++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+)
 create mode 100644 PrefixSum/BasicPrefixSum.js
 create mode 100644 PrefixSum/BasicPrefixSum.test.js

diff --git a/PrefixSum/BasicPrefixSum.js b/PrefixSum/BasicPrefixSum.js
new file mode 100644
index 0000000000..4c47605e5e
--- /dev/null
+++ b/PrefixSum/BasicPrefixSum.js
@@ -0,0 +1,37 @@
+/**
+ * Computes the prefix sum of an array
+ * @param {number[]} arrayOfNumbers - Array of numbers
+ * @returns {number[]} - Prefix sum array
+ * @throws {TypeError} - If input is not a numeric array
+ */
+function basicPrefixSum(arrayOfNumbers) {
+  // Validate input
+  if (!Array.isArray(arrayOfNumbers)) {
+    throw new TypeError('Input must be an array')
+  }
+
+  for (let i = 0; i < arrayOfNumbers.length; i++) {
+    if (
+      typeof arrayOfNumbers[i] !== 'number' ||
+      !Number.isFinite(arrayOfNumbers[i])
+    ) {
+      throw new TypeError('All elements must be finite numbers')
+    }
+  }
+
+  // Handle empty array
+  if (arrayOfNumbers.length === 0) {
+    return []
+  }
+
+  const prefixSum = new Array(arrayOfNumbers.length)
+  prefixSum[0] = arrayOfNumbers[0]
+
+  for (let i = 1; i < arrayOfNumbers.length; i++) {
+    prefixSum[i] = prefixSum[i - 1] + arrayOfNumbers[i]
+  }
+
+  return prefixSum
+}
+
+export default basicPrefixSum
diff --git a/PrefixSum/BasicPrefixSum.test.js b/PrefixSum/BasicPrefixSum.test.js
new file mode 100644
index 0000000000..48674256d9
--- /dev/null
+++ b/PrefixSum/BasicPrefixSum.test.js
@@ -0,0 +1,42 @@
+import { describe, it, expect } from 'vitest'
+import basicPrefixSum from './BasicPrefixSum.js'
+
+describe('BasicPrefixSum', () => {
+  it('should compute prefix sum for normal array', () => {
+    const input = [1, 2, 3, 4, 5]
+    const expected = [1, 3, 6, 10, 15]
+    expect(basicPrefixSum(input)).toEqual(expected)
+  })
+
+  it('should handle empty array', () => {
+    expect(basicPrefixSum([])).toEqual([])
+  })
+
+  it('should handle single element array', () => {
+    expect(basicPrefixSum([5])).toEqual([5])
+  })
+
+  it('should handle negative numbers', () => {
+    const input = [-1, 2, -3, 4]
+    const expected = [-1, 1, -2, 2]
+    expect(basicPrefixSum(input)).toEqual(expected)
+  })
+
+  it('should throw TypeError for non-array input', () => {
+    expect(() => basicPrefixSum('not an array')).toThrow(TypeError)
+    expect(() => basicPrefixSum(123)).toThrow(TypeError)
+    expect(() => basicPrefixSum(null)).toThrow(TypeError)
+  })
+
+  it('should throw TypeError for non-numeric array elements', () => {
+    expect(() => basicPrefixSum([1, 'string', 3])).toThrow(TypeError)
+    expect(() => basicPrefixSum([1, null, 3])).toThrow(TypeError)
+    expect(() => basicPrefixSum([1, undefined, 3])).toThrow(TypeError)
+  })
+
+  it('should throw TypeError for infinite values', () => {
+    expect(() => basicPrefixSum([1, Infinity, 3])).toThrow(TypeError)
+    expect(() => basicPrefixSum([1, -Infinity, 3])).toThrow(TypeError)
+    expect(() => basicPrefixSum([1, NaN, 3])).toThrow(TypeError)
+  })
+})