From 70b0e0a6527c2f0e170c85e4fa980626916ed981 Mon Sep 17 00:00:00 2001
From: Tapasweni Pathak <tapaswenipathak@gmail.com>
Date: Mon, 27 Aug 2018 19:29:43 +0530
Subject: [PATCH] Add ifPowerOf2c (#155)

---
 src/algorithms/math/bits/README.md             | 18 ++++++++++++++++++
 .../math/bits/__test__/ifPowerOf2.test.js      |  8 ++++++++
 src/algorithms/math/bits/ifPowerOf2.js         |  7 +++++++
 3 files changed, 33 insertions(+)
 create mode 100644 src/algorithms/math/bits/__test__/ifPowerOf2.test.js
 create mode 100644 src/algorithms/math/bits/ifPowerOf2.js

diff --git a/src/algorithms/math/bits/README.md b/src/algorithms/math/bits/README.md
index f4173af9..4c5c5148 100644
--- a/src/algorithms/math/bits/README.md
+++ b/src/algorithms/math/bits/README.md
@@ -91,6 +91,23 @@ inverting all of the bits of the number and adding 1 to it.
 
 > See [switchSign.js](switchSign.js) for further details.
 
+#### Power of 2
+
+This method checks if a number provided is power of two. It uses the property that when
+a power of 2 is `&` with power of 2 minus 1, it would return 0 implying that the provided
+number is power of 2.
+
+```
+Number: 4
+Power of 2: True
+
+Number: 1
+Power of 2: False
+```
+
+> See `ifPowerof2` function for further details.
+
+
 #### Multiply Two Numbers
 
 This method multiplies two integer numbers using bitwise operators.
@@ -156,6 +173,7 @@ When we shift 1 four times it will become bigger than 5.
 
 > See [bitLength.js](bitLength.js) for further details.
 
+
 ## References
 
 - [Bit Manipulation on YouTube](https://www.youtube.com/watch?v=NLKQEOgBAnw&t=0s&index=28&list=PLLXdhg_r2hKA7DPDsunoDZ-Z769jWn4R8)
diff --git a/src/algorithms/math/bits/__test__/ifPowerOf2.test.js b/src/algorithms/math/bits/__test__/ifPowerOf2.test.js
new file mode 100644
index 00000000..564abc20
--- /dev/null
+++ b/src/algorithms/math/bits/__test__/ifPowerOf2.test.js
@@ -0,0 +1,8 @@
+import ifPowerOf2 from '../ifPowerOf2';
+
+describe('ifPowerOf2', () => {
+  it('Should return if the number is power of 2 or not', () => {
+    expect(ifPowerOf2(5)).toBe(false);
+    expect(ifPowerOf2(4)).toBe(true);
+  });
+});
diff --git a/src/algorithms/math/bits/ifPowerOf2.js b/src/algorithms/math/bits/ifPowerOf2.js
new file mode 100644
index 00000000..dd29f9f2
--- /dev/null
+++ b/src/algorithms/math/bits/ifPowerOf2.js
@@ -0,0 +1,7 @@
+/**
+ * @param {number} number
+ * @return bool
+ */
+export default function ifPowerOf2(number) {
+  return number && (!(number & (number - 1)));
+}