added prefix sum code and fix prettier

Author: rishima17

Data-Structures/Array/BasicPrefixSum.js

@@ -7,18 +7,18 @@
  */
 export const basicPrefixSum = (arr) => {
   if (!Array.isArray(arr)) {
-    throw new TypeError("Input must be an array");
+    throw new TypeError('Input must be an array')
   }
 
-  if (!arr.every((item) => typeof item === "number")) {
-    throw new TypeError("All elements must be numbers");
+  if (!arr.every((item) => typeof item === 'number')) {
+    throw new TypeError('All elements must be numbers')
   }
 
-  const prefix = [];
-  let sum = 0;
+  const prefix = []
+  let sum = 0
   for (const num of arr) {
-    sum += num;
-    prefix.push(sum);
+    sum += num
+    prefix.push(sum)
   }
-  return prefix;
-};
+  return prefix
+}

Data-Structures/Array/test/BasicPrefixSum.test.js

@@ -1,20 +1,20 @@
-import { describe, it, expect } from "vitest";
-import { basicPrefixSum } from "../BasicPrefixSum.js";
+import { describe, it, expect } from 'vitest'
+import { basicPrefixSum } from '../BasicPrefixSum.js'
 
-describe("basicPrefixSum", () => {
-  it("computes prefix sums correctly", () => {
-    expect(basicPrefixSum([1, 2, 3, 4])).toEqual([1, 3, 6, 10]);
-  });
+describe('basicPrefixSum', () => {
+  it('computes prefix sums correctly', () => {
+    expect(basicPrefixSum([1, 2, 3, 4])).toEqual([1, 3, 6, 10])
+  })
 
-  it("returns an empty array for empty input", () => {
-    expect(basicPrefixSum([])).toEqual([]);
-  });
+  it('returns an empty array for empty input', () => {
+    expect(basicPrefixSum([])).toEqual([])
+  })
 
-  it("throws an error if input is not an array", () => {
-    expect(() => basicPrefixSum("abc")).toThrow(TypeError);
-  });
+  it('throws an error if input is not an array', () => {
+    expect(() => basicPrefixSum('abc')).toThrow(TypeError)
+  })
 
-  it("throws an error if array contains non-numeric elements", () => {
-    expect(() => basicPrefixSum([1, "2", 3])).toThrow(TypeError);
-  });
-});
+  it('throws an error if array contains non-numeric elements', () => {
+    expect(() => basicPrefixSum([1, '2', 3])).toThrow(TypeError)
+  })
+})