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Add get next challenge
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Donne Martin
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commit
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0
bit_manipulation/get_next/__init__.py
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0
bit_manipulation/get_next/__init__.py
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186
bit_manipulation/get_next/get_next_challenge.ipynb
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186
bit_manipulation/get_next/get_next_challenge.ipynb
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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"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)."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Challenge Notebook"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## 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",
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"\n",
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"* [Constraints](#Constraints)\n",
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"* [Test Cases](#Test-Cases)\n",
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"* [Algorithm](#Algorithm)\n",
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"* [Code](#Code)\n",
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"* [Unit Test](#Unit-Test)\n",
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"* [Solution Notebook](#Solution-Notebook)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Constraints\n",
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"\n",
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"* Is the output a positive int?\n",
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" * Yes\n",
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"* Can we assume the inputs are valid?\n",
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" * No\n",
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"* Can we assume this fits memory?\n",
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" * Yes"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Test Cases\n",
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"\n",
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"* None -> Exception\n",
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"* 0 -> Exception\n",
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"* negative int -> Exception\n",
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"* General case:\n",
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"<pre>\n",
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" * Input: 0000 0000 1101 0111\n",
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" * Next largest: 0000 0000 1101 1011\n",
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" * Next smallest: 0000 0000 1100 1111\n",
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"</pre>"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Algorithm\n",
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"\n",
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"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."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Code"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"class Bits(object):\n",
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"\n",
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" def get_next_largest(self, num):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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" def get_next_smallest(self, num):\n",
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" # TODO: Implement me\n",
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" pass"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Unit Test"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"**The following unit test is expected to fail until you solve the challenge.**"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"# %load test_get_next_largest.py\n",
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"from nose.tools import assert_equal, assert_raises\n",
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"\n",
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"\n",
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"class TestBits(object):\n",
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"\n",
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" def test_get_next_largest(self):\n",
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" bits = Bits()\n",
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" assert_raises(Exception, bits.get_next_largest, None)\n",
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" assert_raises(Exception, bits.get_next_largest, 0)\n",
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" assert_raises(Exception, bits.get_next_largest, -1)\n",
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" num = int('011010111', base=2)\n",
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" expected = int('011011011', base=2)\n",
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" assert_equal(bits.get_next_largest(num), expected)\n",
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" print('Success: test_get_next_largest')\n",
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"\n",
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" def test_get_next_smallest(self):\n",
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" bits = Bits()\n",
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" assert_raises(Exception, bits.get_next_smallest, None)\n",
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" assert_raises(Exception, bits.get_next_smallest, 0)\n",
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" assert_raises(Exception, bits.get_next_smallest, -1)\n",
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" num = int('011010111', base=2)\n",
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" expected = int('011001111', base=2)\n",
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" assert_equal(bits.get_next_smallest(num), expected)\n",
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" print('Success: test_get_next_smallest')\n",
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"\n",
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"def main():\n",
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" test = TestBits()\n",
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" test.test_get_next_largest()\n",
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" test.test_get_next_smallest()\n",
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"\n",
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"\n",
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"if __name__ == '__main__':\n",
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" main()"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Solution Notebook\n",
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"\n",
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"Review the [Solution Notebook]() for a discussion on algorithms and code solutions."
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 3",
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"language": "python",
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"name": "python3"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.5.0"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 0
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}
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272
bit_manipulation/get_next/get_next_solution.ipynb
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bit_manipulation/get_next/get_next_solution.ipynb
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@ -0,0 +1,272 @@
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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"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)."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Solution Notebook"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## 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",
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"\n",
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"* [Constraints](#Constraints)\n",
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"* [Test Cases](#Test-Cases)\n",
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"* [Algorithm](#Algorithm)\n",
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"* [Code](#Code)\n",
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"* [Unit Test](#Unit-Test)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Constraints\n",
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"\n",
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"* Is the output a positive int?\n",
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" * Yes\n",
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"* Can we assume the inputs are valid?\n",
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" * No\n",
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"* Can we assume this fits memory?\n",
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" * Yes"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Test Cases\n",
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"\n",
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"* None -> Exception\n",
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"* 0 -> Exception\n",
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"* negative int -> Exception\n",
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"* General case:\n",
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"<pre>\n",
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" * Input: 0000 0000 1101 0111\n",
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" * Next largest: 0000 0000 1101 1011\n",
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" * Next smallest: 0000 0000 1100 1111\n",
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"</pre>"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Algorithm\n",
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"\n",
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"### get_next_largest\n",
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"\n",
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"* Find the right-most non trailing zero, call this index\n",
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" * 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",
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" * Count the number of zeroes to the right of index\n",
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" * While num & 1 == 0 and num_copy != 0:\n",
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" * Increment number of zeroes\n",
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" * Logical shift right num_copy\n",
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" * Count the number of ones to the right of index\n",
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" * While num & 1 == 1 and num_copy != 0:\n",
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" * Increment number of ones\n",
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" * Logical shift right num_copy\n",
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" * The index will be the sum of number of ones and number of zeroes\n",
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" * Set the index bit\n",
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" * Clear all bits to the right of index\n",
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" * Set bits starting from 0\n",
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" * Only set (number of ones - 1) bits because we set index to 1\n",
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"\n",
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"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",
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"\n",
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" num % 0x100000000 >> n\n",
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"\n",
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"### get_next_smallest\n",
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"\n",
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"* The algorithm for finding the next smallest number is very similar to finding the next largest number\n",
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" * Instead of finding the right-most non-trailing zero, we'll find the right most non-trailing one and clear it\n",
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" * Clear all bits to the right of index\n",
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" * Set bits starting at 0 to the number of ones to the right of index, plus one\n",
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"\n",
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"Complexity:\n",
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"* Time: O(b), where b is the number of bits in num\n",
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"* Space: O(b), where b is the number of bits in num"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Code"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"class Bits(object):\n",
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"\n",
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" def get_next_largest(self, num):\n",
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" if num is None:\n",
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" raise TypeError('num cannot be None')\n",
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" if num <= 0:\n",
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" raise ValueError('num cannot be 0 or negative')\n",
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" num_ones = 0\n",
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" num_zeroes = 0\n",
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" num_copy = num\n",
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" # We'll look for index, which is the right-most non-trailing zero\n",
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" # Count number of zeroes to the right of index\n",
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" while num_copy != 0 and num_copy & 1 == 0:\n",
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" num_zeroes += 1\n",
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" num_copy >>= 1\n",
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" # Count number of ones to the right of index\n",
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" while num_copy != 0 and num_copy & 1 == 1:\n",
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" num_ones += 1\n",
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" num_copy >>= 1\n",
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" # Determine index and set the bit\n",
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" index = num_zeroes + num_ones\n",
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" num |= 1 << index\n",
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" # Clear all bits to the right of index\n",
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" num &= ~((1 << index) - 1)\n",
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" # Set bits starting from 0\n",
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" num |= ((1 << num_ones - 1) - 1)\n",
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" return num\n",
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"\n",
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" def get_next_smallest(self, num):\n",
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" if num is None:\n",
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" raise TypeError('num cannot be None')\n",
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" if num <= 0:\n",
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" raise ValueError('num cannot be 0 or negative')\n",
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" num_ones = 0\n",
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" num_zeroes = 0\n",
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" num_copy = num\n",
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" # We'll look for index, which is the right-most non-trailing one\n",
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" # Count number of zeroes to the right of index\n",
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" while num_copy != 0 and num_copy & 1 == 1:\n",
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" num_ones += 1\n",
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" num_copy >>= 1\n",
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" # Count number of zeroes to the right of index\n",
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" while num_copy != 0 and num_copy & 1 == 0:\n",
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" num_zeroes += 1\n",
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" num_copy >>= 1\n",
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" # Determine index and clear the bit\n",
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" index = num_zeroes + num_ones\n",
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" num &= ~(1 << index)\n",
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" # Clear all bits to the right of index\n",
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" num &= ~((1 << index) - 1)\n",
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" # Set bits starting from 0\n",
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" num |= (1 << num_ones + 1) - 1\n",
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" return num"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Unit Test"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 2,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Overwriting test_get_next_largest.py\n"
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]
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}
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],
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"source": [
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"%%writefile test_get_next_largest.py\n",
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"from nose.tools import assert_equal, assert_raises\n",
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"\n",
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"\n",
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"class TestBits(object):\n",
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"\n",
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" def test_get_next_largest(self):\n",
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" bits = Bits()\n",
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" assert_raises(Exception, bits.get_next_largest, None)\n",
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" assert_raises(Exception, bits.get_next_largest, 0)\n",
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" assert_raises(Exception, bits.get_next_largest, -1)\n",
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" num = int('011010111', base=2)\n",
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" expected = int('011011011', base=2)\n",
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" assert_equal(bits.get_next_largest(num), expected)\n",
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" print('Success: test_get_next_largest')\n",
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"\n",
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" def test_get_next_smallest(self):\n",
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" bits = Bits()\n",
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" assert_raises(Exception, bits.get_next_smallest, None)\n",
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" assert_raises(Exception, bits.get_next_smallest, 0)\n",
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" assert_raises(Exception, bits.get_next_smallest, -1)\n",
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" num = int('011010111', base=2)\n",
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" expected = int('011001111', base=2)\n",
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" assert_equal(bits.get_next_smallest(num), expected)\n",
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" print('Success: test_get_next_smallest')\n",
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"\n",
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"def main():\n",
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" test = TestBits()\n",
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" test.test_get_next_largest()\n",
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" test.test_get_next_smallest()\n",
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"\n",
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"\n",
|
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"if __name__ == '__main__':\n",
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" main()"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 3,
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"metadata": {
|
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
|
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"Success: test_get_next_largest\n",
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"Success: test_get_next_smallest\n"
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]
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}
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],
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"source": [
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"%run -i test_get_next_largest.py"
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]
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}
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],
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"metadata": {
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"kernelspec": {
|
||||
"display_name": "Python 3",
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"language": "python",
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"name": "python3"
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},
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"language_info": {
|
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"codemirror_mode": {
|
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"name": "ipython",
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"version": 3
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},
|
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"file_extension": ".py",
|
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.4.3"
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}
|
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},
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"nbformat": 4,
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"nbformat_minor": 0
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}
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33
bit_manipulation/get_next/test_get_next_largest.py
Normal file
33
bit_manipulation/get_next/test_get_next_largest.py
Normal file
@ -0,0 +1,33 @@
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from nose.tools import assert_equal, assert_raises
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class TestBits(object):
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||||
|
||||
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()
|
||||
Loading…
x
Reference in New Issue
Block a user