diff --git a/sorting_searching/new_int/__init__.py b/sorting_searching/new_int/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/sorting_searching/new_int/new_int_challenge.ipynb b/sorting_searching/new_int/new_int_challenge.ipynb
new file mode 100644
index 0000000..31fb42f
--- /dev/null
+++ b/sorting_searching/new_int/new_int_challenge.ipynb
@@ -0,0 +1,174 @@
+{
+ "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 an array of 32 integers, find an int not in the input.  Use a minimal amount of memory.\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",
+    "* Are we working with non-negative ints?\n",
+    "    * Yes\n",
+    "* What is the range of the integers?\n",
+    "    * Discuss the approach for 4 billion integers\n",
+    "    * Implement for 32 integers\n",
+    "* Can we assume the inputs are valid?\n",
+    "    * No"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test Cases\n",
+    "\n",
+    "* None -> Exception\n",
+    "* [] -> Exception\n",
+    "* General case\n",
+    "    * There is an int excluded from the input -> int\n",
+    "    * There isn't an int excluded from the input -> None"
+   ]
+  },
+  {
+   "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": [
+    "from bitstring import BitArray  # run pip install bitstring\n",
+    "\n",
+    "\n",
+    "class Bits(object):\n",
+    "\n",
+    "    def new_int(self, array, max_size):\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_new_int.py\n",
+    "from nose.tools import assert_equal, assert_raises\n",
+    "\n",
+    "\n",
+    "class TestBits(object):\n",
+    "\n",
+    "    def test_new_int(self):\n",
+    "        bits = Bits()\n",
+    "        max_size = 32\n",
+    "        assert_raises(TypeError, bits.new_int, None, max_size)\n",
+    "        assert_raises(TypeError, bits.new_int, [], max_size)\n",
+    "        data = [item for item in range(30)]\n",
+    "        data.append(31)\n",
+    "        assert_equal(bits.new_int(data, max_size), 30)\n",
+    "        data = [item for item in range(32)]\n",
+    "        assert_equal(bits.new_int(data, max_size), None)\n",
+    "        print('Success: test_find_int_excluded_from_input')\n",
+    "\n",
+    "\n",
+    "def main():\n",
+    "    test = TestBits()\n",
+    "    test.test_new_int()\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": "3.4.3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/sorting_searching/new_int/new_int_solution.ipynb b/sorting_searching/new_int/new_int_solution.ipynb
new file mode 100644
index 0000000..0832aa1
--- /dev/null
+++ b/sorting_searching/new_int/new_int_solution.ipynb
@@ -0,0 +1,214 @@
+{
+ "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 an array of n integers, find an int not in the input.  Use a minimal amount of memory.\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",
+    "* Are we working with non-negative ints?\n",
+    "    * Yes\n",
+    "* What is the range of the integers?\n",
+    "    * Discuss the approach for 4 billion integers\n",
+    "    * Implement for 32 integers\n",
+    "* Can we assume the inputs are valid?\n",
+    "    * No"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test Cases\n",
+    "\n",
+    "* None -> Exception\n",
+    "* [] -> Exception\n",
+    "* General case\n",
+    "    * There is an int excluded from the input -> int\n",
+    "    * There isn't an int excluded from the input -> None"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Algorithm\n",
+    "\n",
+    "The problem states to use a minimal amount of memory.  We'll use a bit vector to keep track of the inputs.\n",
+    "\n",
+    "Say we are given 4 billion integers, which is 2^32 integers.  The number of non-negative integers would be 2^31.  With a bit vector, we'll need 4 billion bits to map each integer to a bit.  Say we had only 1 GB of memory or 2^32 bytes.  This would leave us with 8 billion bits.\n",
+    "\n",
+    "To simplify this exercise, we'll work with an input of up to 32 ints that we'll map to a bit vector of 32 bits.\n",
+    "\n",
+    "<pre>\n",
+    "\n",
+    "input = [0, 1, 2, 3, 4...28, 29, 31]\n",
+    "\n",
+    "bytes          [         1          ]  [          2         ] [          3          ] [          4          ]\n",
+    "index       =  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31\n",
+    "bit_vector  =  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  0  1\n",
+    "\n",
+    "result = 30\n",
+    "\n",
+    "* Loop through each item in the input, setting bit_vector[item] = True.\n",
+    "* Loop through the bit_vector, return the first index where bit_vector[item] == False.\n",
+    "\n",
+    "</pre>\n",
+    "\n",
+    "Complexity:\n",
+    "* Time: O(b), where b is the number of bits\n",
+    "* Space: O(b)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Code"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "from bitstring import BitArray  # Run pip install bitstring\n",
+    "\n",
+    "\n",
+    "class Bits(object):\n",
+    "\n",
+    "    def new_int(self, array, max_size):\n",
+    "        if not array:\n",
+    "            raise TypeError('array cannot be None or empty')\n",
+    "        bit_vector = BitArray(max_size)\n",
+    "        for item in array:\n",
+    "            bit_vector[item] = True\n",
+    "        for index, item in enumerate(bit_vector):\n",
+    "            if not item:\n",
+    "                return index\n",
+    "        return None"
+   ]
+  },
+  {
+   "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_new_int.py\n"
+     ]
+    }
+   ],
+   "source": [
+    "%%writefile test_new_int.py\n",
+    "from nose.tools import assert_equal, assert_raises\n",
+    "\n",
+    "\n",
+    "class TestBits(object):\n",
+    "\n",
+    "    def test_new_int(self):\n",
+    "        bits = Bits()\n",
+    "        max_size = 32\n",
+    "        assert_raises(TypeError, bits.new_int, None, max_size)\n",
+    "        assert_raises(TypeError, bits.new_int, [], max_size)\n",
+    "        data = [item for item in range(30)]\n",
+    "        data.append(31)\n",
+    "        assert_equal(bits.new_int(data, max_size), 30)\n",
+    "        data = [item for item in range(32)]\n",
+    "        assert_equal(bits.new_int(data, max_size), None)\n",
+    "        print('Success: test_find_int_excluded_from_input')\n",
+    "\n",
+    "\n",
+    "def main():\n",
+    "    test = TestBits()\n",
+    "    test.test_new_int()\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_find_int_excluded_from_input\n"
+     ]
+    }
+   ],
+   "source": [
+    "%run -i test_new_int.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/sorting_searching/new_int/test_new_int.py b/sorting_searching/new_int/test_new_int.py
new file mode 100644
index 0000000..39c0eda
--- /dev/null
+++ b/sorting_searching/new_int/test_new_int.py
@@ -0,0 +1,25 @@
+from nose.tools import assert_equal, assert_raises
+
+
+class TestBits(object):
+
+    def test_new_int(self):
+        bits = Bits()
+        max_size = 32
+        assert_raises(TypeError, bits.new_int, None, max_size)
+        assert_raises(TypeError, bits.new_int, [], max_size)
+        data = [item for item in range(30)]
+        data.append(31)
+        assert_equal(bits.new_int(data, max_size), 30)
+        data = [item for item in range(32)]
+        assert_equal(bits.new_int(data, max_size), None)
+        print('Success: test_find_int_excluded_from_input')
+
+
+def main():
+    test = TestBits()
+    test.test_new_int()
+
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file