Added BinarySearchIterative Function

* BinarySearchIterative Function is added
* BinarySearch function is renamed to BinarySearchRecurisve
* changes in test function
  - 3 binarySearchRecursive tests
  - 3 binarySearchIterative tests

Author: RitikDua

Search/BinarySearch.js

@@ -7,7 +7,7 @@
  * value is found or the interval is empty.
  */
 
-function binarySearch (arr, x, low = 0, high = arr.length - 1) {
+function binarySearchRecursive (arr, x, low = 0, high = arr.length - 1) {
   const mid = Math.floor(low + (high - low) / 2)
 
   if (high >= low) {
@@ -18,17 +18,40 @@ function binarySearch (arr, x, low = 0, high = arr.length - 1) {
 
     if (x < arr[mid]) {
       // arr[mid] is an upper bound for x, so if x is in arr => low <= x < mid
-      return binarySearch(arr, x, low, mid - 1)
+      return binarySearchRecursive(arr, x, low, mid - 1)
     } else {
       // arr[mid] is a lower bound for x, so if x is in arr => mid < x <= high
-      return binarySearch(arr, x, mid + 1, high)
+      return binarySearchRecursive(arr, x, mid + 1, high)
     }
   } else {
     // if low > high => we have searched the whole array without finding the item
     return -1
   }
 }
 
+function binarySearchIterative (arr, x, low = 0, high = arr.length - 1) {
+  
+  while (high >= low) {
+    const mid = Math.floor(low + (high - low) / 2)
+
+    if (arr[mid] === x) {
+      // item found => return its index
+      return mid
+    }
+
+    if (x < arr[mid]) {
+      // arr[mid] is an upper bound for x, so if x is in arr => low <= x < mid
+      high = mid - 1
+    } else {
+      // arr[mid] is a lower bound for x, so if x is in arr => mid < x <= high
+      low = mid + 1
+    }
+  }
+  // if low > high => we have searched the whole array without finding the item
+  return -1 
+}
+
+
 /* ---------------------------------- Test ---------------------------------- */
 
 const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
@@ -61,10 +84,10 @@ const stringArr = [
   'Zulu'
 ]
 
-console.log(binarySearch(arr, 3))
-console.log(binarySearch(arr, 7))
-console.log(binarySearch(arr, 13))
+console.log(binarySearchRecursive(arr, 3))
+console.log(binarySearchIterative(arr, 7))
+console.log(binarySearchRecursive(arr, 13))
 
-console.log(binarySearch(stringArr, 'Charlie'))
-console.log(binarySearch(stringArr, 'Zulu'))
-console.log(binarySearch(stringArr, 'Sierra'))
+console.log(binarySearchIterative(stringArr, 'Charlie'))
+console.log(binarySearchRecursive(stringArr, 'Zulu'))
+console.log(binarySearchIterative(stringArr, 'Sierra'))