Added partition challenge.

This commit is contained in:
Donne Martin 2015-07-02 23:11:35 -04:00
parent d79ee29ec8
commit c16f25e5f3
4 changed files with 302 additions and 20 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: Partition a linked list around a value x, such that all nodes less than x come before all nodes greater than or equal to x.\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 create additional data structures?\n",
" * Yes\n",
"* Do you expect the function to return a new list?\n",
" * Yes\n",
"* Can we assume the input x is valid?\n",
" * Yes\n",
"* Can we assume we already have a linked list class that can be used for this problem?\n",
" * Yes"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Test Cases\n",
"\n",
"* Empty list -> []\n",
"* One element list -> [element]\n",
"* Left linked list is empty\n",
"* Right linked list is empty\n",
"* General case\n",
" * Partition = 10\n",
" * Input: 4, 3, 7, 8, 10, 1, 10, 12\n",
" * Output: 4, 3, 7, 8, 1, 10, 10, 12"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Algorithm\n",
"\n",
"Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/linked_lists/partition/partition_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": true
},
"outputs": [],
"source": [
"%run ../linked_list/linked_list.py\n",
"%load ../linked_list/linked_list.py"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"class MyLinkedList(LinkedList):\n",
" \n",
" def partition(self, data):\n",
" # TODO: Implement me\n",
" pass"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Unit Test"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"\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_partition.py\n",
"from nose.tools import assert_equal\n",
"\n",
"\n",
"class TestPartition(object):\n",
" \n",
" def test_partition(self):\n",
" print('Test: Empty list')\n",
" linked_list = MyLinkedList(None)\n",
" linked_list.partition(10)\n",
" assert_equal(linked_list.get_all_data(), [])\n",
"\n",
" print('Test: One element list, left list empty')\n",
" linked_list = MyLinkedList(Node(5))\n",
" linked_list.partition(0)\n",
" assert_equal(linked_list.get_all_data(), [5])\n",
"\n",
" print('Test: Right list is empty')\n",
" linked_list = MyLinkedList(Node(5))\n",
" linked_list.partition(10)\n",
" assert_equal(linked_list.get_all_data(), [5])\n",
"\n",
" print('Test: General case')\n",
" # Partition = 10\n",
" # Input: 4, 3, 7, 8, 10, 1, 10, 12\n",
" # Output: 4, 3, 7, 8, 1, 10, 10, 12\n",
" linked_list = MyLinkedList(Node(12))\n",
" linked_list.insert_to_front(10)\n",
" linked_list.insert_to_front(1)\n",
" linked_list.insert_to_front(10)\n",
" linked_list.insert_to_front(8)\n",
" linked_list.insert_to_front(7)\n",
" linked_list.insert_to_front(3)\n",
" linked_list.insert_to_front(4)\n",
" partitioned_list = linked_list.partition(10)\n",
" assert_equal(partitioned_list.get_all_data(), \n",
" [4, 3, 7, 8, 1, 10, 10, 12])\n",
" \n",
" print('Success: test_partition')\n",
"\n",
"def main():\n",
" test = TestPartition()\n",
" test.test_partition()\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/linked_lists/partition/partition_solution.ipynb) for a discussion on algorithms and code solutions."
]
}
],
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"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 create additional data structures?\n",
" * Yes\n",
@ -44,8 +51,8 @@
"source": [
"## Test Cases\n",
"\n",
"* Empty list\n",
"* One element list\n",
"* Empty list -> []\n",
"* One element list -> [element]\n",
"* Left linked list is empty\n",
"* Right linked list is empty\n",
"* General case\n",
@ -86,7 +93,7 @@
},
"outputs": [],
"source": [
"%run linked_list.py"
"%run ../linked_list/linked_list.py"
]
},
{
@ -98,6 +105,7 @@
"outputs": [],
"source": [
"class MyLinkedList(LinkedList):\n",
" \n",
" def partition(self, data):\n",
" if self.head is None:\n",
" return\n",
@ -130,13 +138,6 @@
"## Unit Test"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"*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.*"
]
},
{
"cell_type": "code",
"execution_count": 3,
@ -148,18 +149,17 @@
"name": "stdout",
"output_type": "stream",
"text": [
"Test: Empty list\n",
"Test: One element list, left list empty\n",
"Test: Right list is empty\n",
"Test: General case\n",
"Success: test_partition\n"
"Overwriting test_partition.py\n"
]
}
],
"source": [
"%%writefile test_partition.py\n",
"from nose.tools import assert_equal\n",
"\n",
"class Test(object):\n",
"\n",
"class TestPartition(object):\n",
" \n",
" def test_partition(self):\n",
" print('Test: Empty list')\n",
" linked_list = MyLinkedList(None)\n",
@ -194,9 +194,35 @@
" \n",
" print('Success: test_partition')\n",
"\n",
"def main():\n",
" test = TestPartition()\n",
" test.test_partition()\n",
" \n",
"if __name__ == '__main__':\n",
" test = Test()\n",
" test.test_partition()"
" main()"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Test: Empty list\n",
"Test: One element list, left list empty\n",
"Test: Right list is empty\n",
"Test: General case\n",
"Success: test_partition\n"
]
}
],
"source": [
"run -i test_partition.py"
]
}
],

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from nose.tools import assert_equal
class TestPartition(object):
def test_partition(self):
print('Test: Empty list')
linked_list = MyLinkedList(None)
linked_list.partition(10)
assert_equal(linked_list.get_all_data(), [])
print('Test: One element list, left list empty')
linked_list = MyLinkedList(Node(5))
linked_list.partition(0)
assert_equal(linked_list.get_all_data(), [5])
print('Test: Right list is empty')
linked_list = MyLinkedList(Node(5))
linked_list.partition(10)
assert_equal(linked_list.get_all_data(), [5])
print('Test: General case')
# Partition = 10
# Input: 4, 3, 7, 8, 10, 1, 10, 12
# Output: 4, 3, 7, 8, 1, 10, 10, 12
linked_list = MyLinkedList(Node(12))
linked_list.insert_to_front(10)
linked_list.insert_to_front(1)
linked_list.insert_to_front(10)
linked_list.insert_to_front(8)
linked_list.insert_to_front(7)
linked_list.insert_to_front(3)
linked_list.insert_to_front(4)
partitioned_list = linked_list.partition(10)
assert_equal(partitioned_list.get_all_data(),
[4, 3, 7, 8, 1, 10, 10, 12])
print('Success: test_partition')
def main():
test = TestPartition()
test.test_partition()
if __name__ == '__main__':
main()