feat: add binary search example

Algorithms/binarySearch.js

@@ -0,0 +1,24 @@
+/**
+ * Binary search is an efficient algorithm for finding an item from a sorted list of items.
+ * It works by repeatedly dividing in half the portion of the list that could contain the item,
+ * until you've narrowed down the possible locations to just one.
+ */
+
+function binarySearch(arr, x, left, right) {
+  if (left > right) {
+    return false;
+  }
+
+  const middle = Math.floor(left + (right - left) / 2);
+  if (arr[middle] === x) {
+    return true;
+  } else if (x < arr[middle]) {
+    return binarySearch(arr, x, left, middle - 1);
+  } else {
+    return binarySearch(arr, x, middle + 1, right);
+  }
+}
+
+export default function (arr, x) {
+  return binarySearch(arr, x, 0, arr.length);
+}