From 2fb0d48d94d9b4d14b23f9ed5cfe23410d920e81 Mon Sep 17 00:00:00 2001
From: YATIN KATHURIA <47096348+Yatin-kathuria@users.noreply.github.com>
Date: Fri, 26 Nov 2021 22:08:43 +0530
Subject: [PATCH] merge: Add test cases, optamization of code, and Add
 description of function (#848)

* Add test cases, optamization of code, and Add description of function

* update testcase
---
 Recursive/BinarySearch.js           | 45 ++++++++++++++++++++---------
 Recursive/test/BinarySearch.test.js | 32 ++++++++++++++++++++
 2 files changed, 63 insertions(+), 14 deletions(-)
 create mode 100644 Recursive/test/BinarySearch.test.js

diff --git a/Recursive/BinarySearch.js b/Recursive/BinarySearch.js
index ef24dcba0..6f6e216df 100644
--- a/Recursive/BinarySearch.js
+++ b/Recursive/BinarySearch.js
@@ -1,19 +1,36 @@
 
-// https://en.wikipedia.org/wiki/Binary_search_algorithm
-// Search the integer inside the sorted integers array using Binary Search Algorithm
+/**
+ * @function BinarySearch
+ * @description Search the integer inside the sorted integers array using Binary Search Algorithm.
+ * @param {Integer[]} arr - sorted array of integers
+ * @param {Integer} low - The input integer
+ * @param {Integer} high - The input integer
+ * @param {Integer} searchValue - The input integer
+ * @return {Integer} - return index of searchValue if found else return -1.
+ * @see [BinarySearch](https://en.wikipedia.org/wiki/Binary_search_algorithm)
+ */
 
-export const BinarySearch = (intArr, searchQuery) => {
-  if (searchQuery === null || searchQuery === undefined || intArr.length === 0) {
-    return false
+const binarySearch = (arr, low = 0, high = arr.length - 1, searchValue) => {
+  if (high >= low) {
+    const mid = low + Math.floor((high - low) / 2)
+
+    // If the element is present at the middle
+    if (arr[mid] === searchValue) {
+      return mid
+    }
+
+    // If element is smaller than mid, then
+    // it can only be present in left subarray
+    if (arr[mid] > searchValue) {
+      return binarySearch(arr, low, mid - 1, searchValue)
+    }
+
+    // Else the element can only be present in right subarray
+    return binarySearch(arr, mid + 1, high, searchValue)
   }
 
-  const middleIndex = intArr.length === 1 ? 0 : Math.ceil(intArr.length / 2)
-
-  if (intArr[middleIndex] === searchQuery) {
-    return true
-  } else if (intArr.length > 1) {
-    return intArr[middleIndex] < searchQuery ? BinarySearch(intArr.slice(1, middleIndex)) : BinarySearch(intArr.slice(middleIndex))
-  } else {
-    return false
-  }
+  // We reach here when element is not present in array
+  return -1
 }
+
+export { binarySearch }
diff --git a/Recursive/test/BinarySearch.test.js b/Recursive/test/BinarySearch.test.js
new file mode 100644
index 000000000..2efc92c2e
--- /dev/null
+++ b/Recursive/test/BinarySearch.test.js
@@ -0,0 +1,32 @@
+import { binarySearch } from '../BinarySearch'
+
+describe('BinarySearch', () => {
+  const arr = [2, 3, 4, 10, 25, 40, 45, 60, 100, 501, 700, 755, 800, 999]
+  const low = 0
+  const high = arr.length - 1
+
+  it('should return index 3 for searchValue 10', () => {
+    const searchValue = 10
+    expect(binarySearch(arr, low, high, searchValue)).toBe(3)
+  })
+
+  it('should return index 0 for searchValue 2', () => {
+    const searchValue = 2
+    expect(binarySearch(arr, low, high, searchValue)).toBe(0)
+  })
+
+  it('should return index 13 for searchValue 999', () => {
+    const searchValue = 999
+    expect(binarySearch(arr, low, high, searchValue)).toBe(13)
+  })
+
+  it('should return -1 for searchValue 1', () => {
+    const searchValue = 1
+    expect(binarySearch(arr, low, high, searchValue)).toBe(-1)
+  })
+
+  it('should return -1 for searchValue 1000', () => {
+    const searchValue = 1000
+    expect(binarySearch(arr, low, high, searchValue)).toBe(-1)
+  })
+})