Added hanoi challenge.

This commit is contained in:
Donne Martin 2015-07-02 23:03:04 -04:00
parent 129c7a889f
commit 88eb5a9895
4 changed files with 271 additions and 15 deletions

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{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://github.com/donnemartin/coding-challenges).</i></small>"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Challenge Notebook"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Problem: Implement the [Towers of Hanoi](http://en.wikipedia.org/wiki/Tower_of_Hanoi) with 3 towers and N disks.\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",
"*Problem statements are sometimes ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
"\n",
"* Can we assume we already have a stack class that can be used for this problem?\n",
" * Yes"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Test Cases\n",
"\n",
"* NULL tower(s)\n",
"* 0 disks\n",
"* 1 disk\n",
"* 2 or more disks"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Algorithm\n",
"\n",
"Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/stacks_queues/hanoi/hanoi_solution.ipynb). 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": [
"%run ../stack/stack.py\n",
"%load ../stack/stack.py"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"def hanoi(num_disks, src, dest, buff):\n",
" # TODO: Implement me\n",
" pass"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Unit Test\n",
"\n",
"\n",
"\n",
"**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_hanoi.py\n",
"from nose.tools import assert_equal\n",
"\n",
"\n",
"class TestHanoi(object):\n",
" \n",
" def test_hanoi(self):\n",
" num_disks = 3\n",
" src = Stack()\n",
" buff = Stack()\n",
" dest = Stack()\n",
"\n",
" print('Test: NULL towers')\n",
" hanoi(num_disks, None, None, None)\n",
"\n",
" print('Test: 0 disks')\n",
" hanoi(num_disks, src, dest, buff)\n",
" assert_equal(dest.pop(), None)\n",
"\n",
" print('Test: 1 disk')\n",
" src.push(5)\n",
" hanoi(num_disks, src, dest, buff)\n",
" assert_equal(dest.pop(), 5)\n",
"\n",
" print('Test: 2 or more disks')\n",
" for i in xrange(num_disks, -1, -1):\n",
" src.push(i)\n",
" hanoi(num_disks, src, dest, buff)\n",
" for i in xrange(0, num_disks):\n",
" assert_equal(dest.pop(), i)\n",
"\n",
" print('Success: test_hanoi')\n",
"\n",
"def main():\n",
" test = TestHanoi()\n",
" test.test_hanoi()\n",
" \n",
"if __name__ == '__main__':\n",
" main()"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Solution Notebook\n",
"\n",
"Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/stacks_queues/hanoi/hanoi_solution.ipynb) for a discussion on algorithms and code solutions."
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 2",
"language": "python",
"name": "python2"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 2
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython2",
"version": "2.7.10"
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"nbformat": 4,
"nbformat_minor": 0
}

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@ -4,7 +4,14 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes).</i></small>"
"<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://github.com/donnemartin/coding-challenges).</i></small>"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Solution Notebook"
]
},
{
@ -26,7 +33,7 @@
"source": [
"## Constraints\n",
"\n",
"*Problem statements are often intentionally ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
"*Problem statements are sometimes ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
"\n",
"* Can we assume we already have a stack class that can be used for this problem?\n",
" * Yes"
@ -38,7 +45,7 @@
"source": [
"## Test Cases\n",
"\n",
"* NULL towers\n",
"* NULL tower(s)\n",
"* 0 disks\n",
"* 1 disk\n",
"* 2 or more disks"
@ -73,11 +80,11 @@
"cell_type": "code",
"execution_count": 1,
"metadata": {
"collapsed": true
"collapsed": false
},
"outputs": [],
"source": [
"%run stack.py"
"%run ../stack/stack.py"
]
},
{
@ -103,8 +110,7 @@
"metadata": {},
"source": [
"## Unit Test\n",
"\n",
"*It is important to identify and run through general and edge cases from the [Test Cases](#Test-Cases) section by hand. You generally will not be asked to write a unit test like what is shown below.*"
"\n"
]
},
{
@ -118,18 +124,17 @@
"name": "stdout",
"output_type": "stream",
"text": [
"Test: NULL towers\n",
"Test: 0 disks\n",
"Test: 1 disk\n",
"Test: 2 or more disks\n",
"Success: test_hanoi\n"
"Overwriting test_hanoi.py\n"
]
}
],
"source": [
"%%writefile test_hanoi.py\n",
"from nose.tools import assert_equal\n",
"\n",
"class Test(object):\n",
"\n",
"class TestHanoi(object):\n",
" \n",
" def test_hanoi(self):\n",
" num_disks = 3\n",
" src = Stack()\n",
@ -157,9 +162,35 @@
"\n",
" print('Success: test_hanoi')\n",
"\n",
"def main():\n",
" test = TestHanoi()\n",
" test.test_hanoi()\n",
" \n",
"if __name__ == '__main__':\n",
" test = Test()\n",
" test.test_hanoi()"
" main()"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Test: NULL towers\n",
"Test: 0 disks\n",
"Test: 1 disk\n",
"Test: 2 or more disks\n",
"Success: test_hanoi\n"
]
}
],
"source": [
"%run -i test_hanoi.py"
]
}
],

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from nose.tools import assert_equal
class TestHanoi(object):
def test_hanoi(self):
num_disks = 3
src = Stack()
buff = Stack()
dest = Stack()
print('Test: NULL towers')
hanoi(num_disks, None, None, None)
print('Test: 0 disks')
hanoi(num_disks, src, dest, buff)
assert_equal(dest.pop(), None)
print('Test: 1 disk')
src.push(5)
hanoi(num_disks, src, dest, buff)
assert_equal(dest.pop(), 5)
print('Test: 2 or more disks')
for i in xrange(num_disks, -1, -1):
src.push(i)
hanoi(num_disks, src, dest, buff)
for i in xrange(0, num_disks):
assert_equal(dest.pop(), i)
print('Success: test_hanoi')
def main():
test = TestHanoi()
test.test_hanoi()
if __name__ == '__main__':
main()