diff --git a/bit_manipulation/get_next/__init__.py b/bit_manipulation/get_next/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/bit_manipulation/get_next/get_next_challenge.ipynb b/bit_manipulation/get_next/get_next_challenge.ipynb
new file mode 100644
index 0000000..265dafd
--- /dev/null
+++ b/bit_manipulation/get_next/get_next_challenge.ipynb
@@ -0,0 +1,186 @@
+{
+ "cells": [
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "# Challenge Notebook"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Problem: Given a positive integer, get the next largest number and the next smallest number with the same number of 1's as the given number.\n",
+ "\n",
+ "* [Constraints](#Constraints)\n",
+ "* [Test Cases](#Test-Cases)\n",
+ "* [Algorithm](#Algorithm)\n",
+ "* [Code](#Code)\n",
+ "* [Unit Test](#Unit-Test)\n",
+ "* [Solution Notebook](#Solution-Notebook)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Constraints\n",
+ "\n",
+ "* Is the output a positive int?\n",
+ " * Yes\n",
+ "* Can we assume the inputs are valid?\n",
+ " * No\n",
+ "* Can we assume this fits memory?\n",
+ " * Yes"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Test Cases\n",
+ "\n",
+ "* None -> Exception\n",
+ "* 0 -> Exception\n",
+ "* negative int -> Exception\n",
+ "* General case:\n",
+ "\n",
+ " * Input: 0000 0000 1101 0111\n",
+ " * Next largest: 0000 0000 1101 1011\n",
+ " * Next smallest: 0000 0000 1100 1111\n",
+ "
"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Algorithm\n",
+ "\n",
+ "Refer to the [Solution Notebook](). If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Code"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "class Bits(object):\n",
+ "\n",
+ " def get_next_largest(self, num):\n",
+ " # TODO: Implement me\n",
+ " pass\n",
+ "\n",
+ " def get_next_smallest(self, num):\n",
+ " # TODO: Implement me\n",
+ " pass"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Unit Test"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "**The following unit test is expected to fail until you solve the challenge.**"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# %load test_get_next_largest.py\n",
+ "from nose.tools import assert_equal, assert_raises\n",
+ "\n",
+ "\n",
+ "class TestBits(object):\n",
+ "\n",
+ " def test_get_next_largest(self):\n",
+ " bits = Bits()\n",
+ " assert_raises(Exception, bits.get_next_largest, None)\n",
+ " assert_raises(Exception, bits.get_next_largest, 0)\n",
+ " assert_raises(Exception, bits.get_next_largest, -1)\n",
+ " num = int('011010111', base=2)\n",
+ " expected = int('011011011', base=2)\n",
+ " assert_equal(bits.get_next_largest(num), expected)\n",
+ " print('Success: test_get_next_largest')\n",
+ "\n",
+ " def test_get_next_smallest(self):\n",
+ " bits = Bits()\n",
+ " assert_raises(Exception, bits.get_next_smallest, None)\n",
+ " assert_raises(Exception, bits.get_next_smallest, 0)\n",
+ " assert_raises(Exception, bits.get_next_smallest, -1)\n",
+ " num = int('011010111', base=2)\n",
+ " expected = int('011001111', base=2)\n",
+ " assert_equal(bits.get_next_smallest(num), expected)\n",
+ " print('Success: test_get_next_smallest')\n",
+ "\n",
+ "def main():\n",
+ " test = TestBits()\n",
+ " test.test_get_next_largest()\n",
+ " test.test_get_next_smallest()\n",
+ "\n",
+ "\n",
+ "if __name__ == '__main__':\n",
+ " main()"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Solution Notebook\n",
+ "\n",
+ "Review the [Solution Notebook]() for a discussion on algorithms and code solutions."
+ ]
+ }
+ ],
+ "metadata": {
+ "kernelspec": {
+ "display_name": "Python 3",
+ "language": "python",
+ "name": "python3"
+ },
+ "language_info": {
+ "codemirror_mode": {
+ "name": "ipython",
+ "version": 3
+ },
+ "file_extension": ".py",
+ "mimetype": "text/x-python",
+ "name": "python",
+ "nbconvert_exporter": "python",
+ "pygments_lexer": "ipython3",
+ "version": "3.5.0"
+ }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/bit_manipulation/get_next/get_next_solution.ipynb b/bit_manipulation/get_next/get_next_solution.ipynb
new file mode 100644
index 0000000..fa87ce3
--- /dev/null
+++ b/bit_manipulation/get_next/get_next_solution.ipynb
@@ -0,0 +1,272 @@
+{
+ "cells": [
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "# Solution Notebook"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Problem: Given a positive integer, get the next largest number and the next smallest number with the same number of 1's as the given number.\n",
+ "\n",
+ "* [Constraints](#Constraints)\n",
+ "* [Test Cases](#Test-Cases)\n",
+ "* [Algorithm](#Algorithm)\n",
+ "* [Code](#Code)\n",
+ "* [Unit Test](#Unit-Test)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Constraints\n",
+ "\n",
+ "* Is the output a positive int?\n",
+ " * Yes\n",
+ "* Can we assume the inputs are valid?\n",
+ " * No\n",
+ "* Can we assume this fits memory?\n",
+ " * Yes"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Test Cases\n",
+ "\n",
+ "* None -> Exception\n",
+ "* 0 -> Exception\n",
+ "* negative int -> Exception\n",
+ "* General case:\n",
+ "\n",
+ " * Input: 0000 0000 1101 0111\n",
+ " * Next largest: 0000 0000 1101 1011\n",
+ " * Next smallest: 0000 0000 1100 1111\n",
+ "
"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Algorithm\n",
+ "\n",
+ "### get_next_largest\n",
+ "\n",
+ "* Find the right-most non trailing zero, call this index\n",
+ " * We'll use a mask of 1 and do a logical right shift on a copy of num to examine each bit starting from the right\n",
+ " * Count the number of zeroes to the right of index\n",
+ " * While num & 1 == 0 and num_copy != 0:\n",
+ " * Increment number of zeroes\n",
+ " * Logical shift right num_copy\n",
+ " * Count the number of ones to the right of index\n",
+ " * While num & 1 == 1 and num_copy != 0:\n",
+ " * Increment number of ones\n",
+ " * Logical shift right num_copy\n",
+ " * The index will be the sum of number of ones and number of zeroes\n",
+ " * Set the index bit\n",
+ " * Clear all bits to the right of index\n",
+ " * Set bits starting from 0\n",
+ " * Only set (number of ones - 1) bits because we set index to 1\n",
+ "\n",
+ "We should make a note that Python does not have a logical right shift operator built in. We can either use a positive number of implement one for a 32 bit number:\n",
+ "\n",
+ " num % 0x100000000 >> n\n",
+ "\n",
+ "### get_next_smallest\n",
+ "\n",
+ "* The algorithm for finding the next smallest number is very similar to finding the next largest number\n",
+ " * Instead of finding the right-most non-trailing zero, we'll find the right most non-trailing one and clear it\n",
+ " * Clear all bits to the right of index\n",
+ " * Set bits starting at 0 to the number of ones to the right of index, plus one\n",
+ "\n",
+ "Complexity:\n",
+ "* Time: O(b), where b is the number of bits in num\n",
+ "* Space: O(b), where b is the number of bits in num"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Code"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 1,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "class Bits(object):\n",
+ "\n",
+ " def get_next_largest(self, num):\n",
+ " if num is None:\n",
+ " raise TypeError('num cannot be None')\n",
+ " if num <= 0:\n",
+ " raise ValueError('num cannot be 0 or negative')\n",
+ " num_ones = 0\n",
+ " num_zeroes = 0\n",
+ " num_copy = num\n",
+ " # We'll look for index, which is the right-most non-trailing zero\n",
+ " # Count number of zeroes to the right of index\n",
+ " while num_copy != 0 and num_copy & 1 == 0:\n",
+ " num_zeroes += 1\n",
+ " num_copy >>= 1\n",
+ " # Count number of ones to the right of index\n",
+ " while num_copy != 0 and num_copy & 1 == 1:\n",
+ " num_ones += 1\n",
+ " num_copy >>= 1\n",
+ " # Determine index and set the bit\n",
+ " index = num_zeroes + num_ones\n",
+ " num |= 1 << index\n",
+ " # Clear all bits to the right of index\n",
+ " num &= ~((1 << index) - 1)\n",
+ " # Set bits starting from 0\n",
+ " num |= ((1 << num_ones - 1) - 1)\n",
+ " return num\n",
+ "\n",
+ " def get_next_smallest(self, num):\n",
+ " if num is None:\n",
+ " raise TypeError('num cannot be None')\n",
+ " if num <= 0:\n",
+ " raise ValueError('num cannot be 0 or negative')\n",
+ " num_ones = 0\n",
+ " num_zeroes = 0\n",
+ " num_copy = num\n",
+ " # We'll look for index, which is the right-most non-trailing one\n",
+ " # Count number of zeroes to the right of index\n",
+ " while num_copy != 0 and num_copy & 1 == 1:\n",
+ " num_ones += 1\n",
+ " num_copy >>= 1\n",
+ " # Count number of zeroes to the right of index\n",
+ " while num_copy != 0 and num_copy & 1 == 0:\n",
+ " num_zeroes += 1\n",
+ " num_copy >>= 1\n",
+ " # Determine index and clear the bit\n",
+ " index = num_zeroes + num_ones\n",
+ " num &= ~(1 << index)\n",
+ " # Clear all bits to the right of index\n",
+ " num &= ~((1 << index) - 1)\n",
+ " # Set bits starting from 0\n",
+ " num |= (1 << num_ones + 1) - 1\n",
+ " return num"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Unit Test"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 2,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Overwriting test_get_next_largest.py\n"
+ ]
+ }
+ ],
+ "source": [
+ "%%writefile test_get_next_largest.py\n",
+ "from nose.tools import assert_equal, assert_raises\n",
+ "\n",
+ "\n",
+ "class TestBits(object):\n",
+ "\n",
+ " def test_get_next_largest(self):\n",
+ " bits = Bits()\n",
+ " assert_raises(Exception, bits.get_next_largest, None)\n",
+ " assert_raises(Exception, bits.get_next_largest, 0)\n",
+ " assert_raises(Exception, bits.get_next_largest, -1)\n",
+ " num = int('011010111', base=2)\n",
+ " expected = int('011011011', base=2)\n",
+ " assert_equal(bits.get_next_largest(num), expected)\n",
+ " print('Success: test_get_next_largest')\n",
+ "\n",
+ " def test_get_next_smallest(self):\n",
+ " bits = Bits()\n",
+ " assert_raises(Exception, bits.get_next_smallest, None)\n",
+ " assert_raises(Exception, bits.get_next_smallest, 0)\n",
+ " assert_raises(Exception, bits.get_next_smallest, -1)\n",
+ " num = int('011010111', base=2)\n",
+ " expected = int('011001111', base=2)\n",
+ " assert_equal(bits.get_next_smallest(num), expected)\n",
+ " print('Success: test_get_next_smallest')\n",
+ "\n",
+ "def main():\n",
+ " test = TestBits()\n",
+ " test.test_get_next_largest()\n",
+ " test.test_get_next_smallest()\n",
+ "\n",
+ "\n",
+ "if __name__ == '__main__':\n",
+ " main()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 3,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Success: test_get_next_largest\n",
+ "Success: test_get_next_smallest\n"
+ ]
+ }
+ ],
+ "source": [
+ "%run -i test_get_next_largest.py"
+ ]
+ }
+ ],
+ "metadata": {
+ "kernelspec": {
+ "display_name": "Python 3",
+ "language": "python",
+ "name": "python3"
+ },
+ "language_info": {
+ "codemirror_mode": {
+ "name": "ipython",
+ "version": 3
+ },
+ "file_extension": ".py",
+ "mimetype": "text/x-python",
+ "name": "python",
+ "nbconvert_exporter": "python",
+ "pygments_lexer": "ipython3",
+ "version": "3.4.3"
+ }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/bit_manipulation/get_next/test_get_next_largest.py b/bit_manipulation/get_next/test_get_next_largest.py
new file mode 100644
index 0000000..0fd11e2
--- /dev/null
+++ b/bit_manipulation/get_next/test_get_next_largest.py
@@ -0,0 +1,33 @@
+from nose.tools import assert_equal, assert_raises
+
+
+class TestBits(object):
+
+ def test_get_next_largest(self):
+ bits = Bits()
+ assert_raises(Exception, bits.get_next_largest, None)
+ assert_raises(Exception, bits.get_next_largest, 0)
+ assert_raises(Exception, bits.get_next_largest, -1)
+ num = int('011010111', base=2)
+ expected = int('011011011', base=2)
+ assert_equal(bits.get_next_largest(num), expected)
+ print('Success: test_get_next_largest')
+
+ def test_get_next_smallest(self):
+ bits = Bits()
+ assert_raises(Exception, bits.get_next_smallest, None)
+ assert_raises(Exception, bits.get_next_smallest, 0)
+ assert_raises(Exception, bits.get_next_smallest, -1)
+ num = int('011010111', base=2)
+ expected = int('011001111', base=2)
+ assert_equal(bits.get_next_smallest(num), expected)
+ print('Success: test_get_next_smallest')
+
+def main():
+ test = TestBits()
+ test.test_get_next_largest()
+ test.test_get_next_smallest()
+
+
+if __name__ == '__main__':
+ main()
\ No newline at end of file