mirror of
https://github.com/donnemartin/interactive-coding-challenges
synced 2026-01-07 01:48:02 +00:00
Add add digits challenge
This commit is contained in:
Donne Martin
0
math_probability/add_digits/__init__.py
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0
math_probability/add_digits/__init__.py
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176
math_probability/add_digits/add_digits_challenge.ipynb
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176
math_probability/add_digits/add_digits_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 an int, repeatedly add its digits until the result is one digit.\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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"* Can we assume num is not negative?\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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"<pre>\n",
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"* None input -> TypeError\n",
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"* negative input -> ValueError\n",
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"* 9 -> 9\n",
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"* 138 -> 3\n",
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"* 65536 -> 7\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 Solution(object):\n",
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"\n",
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" def add_digits(self, val):\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_add_digits.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 TestAddDigits(object):\n",
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"\n",
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" def test_add_digits(self, func):\n",
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" assert_raises(TypeError, func, None)\n",
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" assert_raises(ValueError, func, -1)\n",
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" assert_equal(func(0), 0)\n",
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" assert_equal(func(9), 9)\n",
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" assert_equal(func(138), 3)\n",
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" assert_equal(func(65536), 7) \n",
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" print('Success: test_add_digits')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestAddDigits()\n",
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" solution = Solution()\n",
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" test.test_add_digits(solution.add_digits)\n",
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" try:\n",
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" test.test_add_digits(solution.add_digits_optimized)\n",
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" except NameError:\n",
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" # Alternate solutions are only defined\n",
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" # in the solutions file\n",
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" pass\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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224
math_probability/add_digits/add_digits_solution.ipynb
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224
math_probability/add_digits/add_digits_solution.ipynb
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@@ -0,0 +1,224 @@
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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 an int, repeatedly add its digits until the result is one digit.\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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"* Can we assume num is not negative?\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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"<pre>\n",
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"* None input -> TypeError\n",
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"* negative input -> ValueError\n",
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"* 9 -> 9\n",
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"* 138 -> 3\n",
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"* 65536 -> 7\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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"The naive solution simply isolates each digit with with modulo and integer division. We'll add each isolated digit to a list and sum the values.\n",
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"\n",
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"<pre>\n",
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"138 % 10 = 8 -> isolated\n",
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"138 // 10 = 13\n",
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"13 % 10 = 3 -> isolated\n",
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"13 // 10 = 1\n",
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"1 % 10 = 1 -> isolated\n",
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"</pre>\n",
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"\n",
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"A more optimal solution exists, by recognizing this is a digital root. See the [Wikipedia article](https://en.wikipedia.org/wiki/Digital_root) for more information.\n",
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"\n",
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"Complexity:\n",
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"* Time: O(1)\n",
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"* Space: O(1)"
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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 Solution(object):\n",
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"\n",
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" def add_digits(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 negative')\n",
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" digits = []\n",
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" while num != 0:\n",
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" digits.append(num % 10)\n",
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" num //= 10\n",
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" digits_sum = sum(digits)\n",
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" if digits_sum >= 10:\n",
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" return self.add_digits(digits_sum)\n",
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" else:\n",
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" return digits_sum\n",
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"\n",
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" def add_digits_optimized(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 negative')\n",
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" if num == 0:\n",
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" return 0\n",
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" elif num % 9 == 0:\n",
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" return 9\n",
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" else:\n",
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" return num % 9"
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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_add_digits.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_add_digits.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 TestAddDigits(object):\n",
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"\n",
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" def test_add_digits(self, func):\n",
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" assert_raises(TypeError, func, None)\n",
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" assert_raises(ValueError, func, -1)\n",
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" assert_equal(func(0), 0)\n",
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" assert_equal(func(9), 9)\n",
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" assert_equal(func(138), 3)\n",
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" assert_equal(func(65536), 7) \n",
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" print('Success: test_add_digits')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestAddDigits()\n",
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" solution = Solution()\n",
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" test.test_add_digits(solution.add_digits)\n",
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" try:\n",
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" test.test_add_digits(solution.add_digits_optimized)\n",
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" except NameError:\n",
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" # Alternate solutions are only defined\n",
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" # in the solutions file\n",
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" pass\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_add_digits\n",
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"Success: test_add_digits\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_add_digits.py"
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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": "3.4.3"
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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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29
math_probability/add_digits/test_add_digits.py
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29
math_probability/add_digits/test_add_digits.py
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@@ -0,0 +1,29 @@
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from nose.tools import assert_equal, assert_raises
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class TestAddDigits(object):
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def test_add_digits(self, func):
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assert_raises(TypeError, func, None)
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assert_raises(ValueError, func, -1)
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assert_equal(func(0), 0)
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assert_equal(func(9), 9)
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assert_equal(func(138), 3)
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assert_equal(func(65536), 7)
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print('Success: test_add_digits')
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def main():
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test = TestAddDigits()
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solution = Solution()
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test.test_add_digits(solution.add_digits)
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try:
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test.test_add_digits(solution.add_digits_optimized)
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except NameError:
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# Alternate solutions are only defined
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# in the solutions file
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pass
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if __name__ == '__main__':
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main()
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Reference in New Issue
Block a user