interactive-coding-challenges/recursion_dynamic/hanoi/hanoi_challenge.ipynb

189 lines
4.7 KiB
Python

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"cell_type": "markdown",
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"source": [
"This notebook was prepared by [Donne Martin](http://donnemartin.com). 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: 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",
"* Can we assume we already have a stack class that can be used for this problem?\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 tower(s) -> Exception\n",
"* 0 disks -> None\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/interactive-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": {},
"outputs": [],
"source": [
"%run ../../stacks_queues/stack/stack.py\n",
"%load ../../stacks_queues/stack/stack.py"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
"outputs": [],
"source": [
"class Hanoi(object):\n",
"\n",
" def move_disks(self, 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": {},
"outputs": [],
"source": [
"# %load test_hanoi.py\n",
"import unittest\n",
"\n",
"\n",
"class TestHanoi(unittest.TestCase):\n",
"\n",
" def test_hanoi(self):\n",
" hanoi = Hanoi()\n",
" num_disks = 3\n",
" src = Stack()\n",
" buff = Stack()\n",
" dest = Stack()\n",
"\n",
" print('Test: None towers')\n",
" self.assertRaises(TypeError, hanoi.move_disks, num_disks, None, None, None)\n",
"\n",
" print('Test: 0 disks')\n",
" hanoi.move_disks(num_disks, src, dest, buff)\n",
" self.assertEqual(dest.pop(), None)\n",
"\n",
" print('Test: 1 disk')\n",
" src.push(5)\n",
" hanoi.move_disks(num_disks, src, dest, buff)\n",
" self.assertEqual(dest.pop(), 5)\n",
"\n",
" print('Test: 2 or more disks')\n",
" for disk_index in range(num_disks, -1, -1):\n",
" src.push(disk_index)\n",
" hanoi.move_disks(num_disks, src, dest, buff)\n",
" for disk_index in range(0, num_disks):\n",
" self.assertEqual(dest.pop(), disk_index)\n",
"\n",
" print('Success: test_hanoi')\n",
"\n",
"\n",
"def main():\n",
" test = TestHanoi()\n",
" test.test_hanoi()\n",
"\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/interactive-coding-challenges/blob/master/stacks_queues/hanoi/hanoi_solution.ipynb) for a discussion on algorithms and code solutions."
]
}
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