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Added stack challenge.

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Donne Martin 2015-07-02 23:06:52 -04:00
parent 8434c7d9f9
commit ba48e81bda
5 changed files with 305 additions and 13 deletions
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0
stacks_queues/stack/__init__.py Normal file
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3
stacks_queues/stack/stack.py
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@ -1,10 +1,11 @@
class Node(object): class Node(object):
def __init__(self, data): def __init__(self, data):
self.data = data self.data = data
self.next = None self.next = None
class Stack(object): class Stack(object):
def __init__(self, top=None): def __init__(self, top=None):
self.top = top self.top = top

218
stacks_queues/stack/stack_challenge.ipynb Normal file
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@ -0,0 +1,218 @@
{
"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 a stack with push, pop, peek, and is_empty methods using a linked list.\n",
"\n",
"* [Constraints](#Constraints)\n",
"* [Test Cases](#Test-Cases)\n",
"* [Algorithm](#Algorithm)\n",
"* [Code](#Code)\n",
"* [Unit Test](#Unit-Test)\n",
"* [Pythonic-Code](#Pythonic-Code)\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",
"* None"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Test Cases\n",
"\n",
"### Push\n",
"\n",
"* Push to empty stack\n",
"* Push to non-empty stack\n",
"\n",
"### Pop\n",
"\n",
"* Pop on empty stack\n",
"* Pop on single element stack\n",
"* Pop on multiple element stack\n",
"\n",
"### Peek\n",
"\n",
"* Peek on empty stack\n",
"* Peek on one or more element stack\n",
"\n",
"### Is Empty\n",
"\n",
"* Is empty on empty stack\n",
"* Is empty on one or more element stack"
]
},
{
"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/stack/stack_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": [
"class Node(object):\n",
" \n",
" def __init__(self, data):\n",
" # TODO: Implement me\n",
" pass\n",
"\n",
"class Stack(object):\n",
" \n",
" def __init__(self, top=None):\n",
" # TODO: Implement me\n",
" pass\n",
"\n",
" def push(self, data):\n",
" # TODO: Implement me\n",
" pass\n",
"\n",
" def pop(self):\n",
" # TODO: Implement me\n",
" pass\n",
"\n",
" def peek(self):\n",
" # TODO: Implement me\n",
" pass\n",
"\n",
" def is_empty(self):\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_stack.py\n",
"from nose.tools import assert_equal\n",
"\n",
"\n",
"class TestStack(object):\n",
" \n",
" # TODO: It would be better if we had unit tests for each\n",
" # method in addition to the following end-to-end test\n",
" def test_end_to_end(self):\n",
" print('Test: Empty stack')\n",
" stack = Stack()\n",
" assert_equal(stack.peek(), None)\n",
" assert_equal(stack.pop(), None)\n",
"\n",
" print('Test: One element')\n",
" top = Node(5)\n",
" stack = Stack(top)\n",
" assert_equal(stack.pop(), 5)\n",
" assert_equal(stack.peek(), None)\n",
"\n",
" print('Test: More than one element')\n",
" stack = Stack()\n",
" stack.push(1)\n",
" stack.push(2)\n",
" stack.push(3)\n",
" assert_equal(stack.pop(), 3)\n",
" assert_equal(stack.peek(), 2)\n",
" assert_equal(stack.pop(), 2)\n",
" assert_equal(stack.peek(), 1)\n",
" assert_equal(stack.is_empty(), False)\n",
" assert_equal(stack.pop(), 1)\n",
" assert_equal(stack.peek(), None)\n",
" assert_equal(stack.is_empty(), True)\n",
" \n",
" print('Success: test_end_to_end')\n",
"\n",
"def main():\n",
" test = TestStack()\n",
" test.test_end_to_end()\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/stack/stack_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"
}
},
"nbformat": 4,
"nbformat_minor": 0
}

56
stacks_queues/stack/stack_solution.ipynb
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@ -4,7 +4,14 @@
"cell_type": "markdown", "cell_type": "markdown",
"metadata": {}, "metadata": {},
"source": [ "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"
] ]
}, },
{ {
@ -27,7 +34,7 @@
"source": [ "source": [
"## Constraints\n", "## Constraints\n",
"\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", "\n",
"* None" "* None"
] ]
@ -130,13 +137,14 @@
], ],
"source": [ "source": [
"%%writefile stack.py\n", "%%writefile stack.py\n",
"\n",
"class Node(object):\n", "class Node(object):\n",
" \n",
" def __init__(self, data):\n", " def __init__(self, data):\n",
" self.data = data\n", " self.data = data\n",
" self.next = None\n", " self.next = None\n",
"\n", "\n",
"class Stack(object):\n", "class Stack(object):\n",
" \n",
" def __init__(self, top=None):\n", " def __init__(self, top=None):\n",
" self.top = top\n", " self.top = top\n",
"\n", "\n",
@ -177,8 +185,7 @@
"metadata": {}, "metadata": {},
"source": [ "source": [
"## Unit Test\n", "## Unit Test\n",
"\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.*"
] ]
}, },
{ {
@ -192,17 +199,17 @@
"name": "stdout", "name": "stdout",
"output_type": "stream", "output_type": "stream",
"text": [ "text": [
"Test: Empty stack\n", "Overwriting test_stack.py\n"
"Test: One element\n",
"Test: More than one element\n",
"Success: test_end_to_end\n"
] ]
} }
], ],
"source": [ "source": [
"%%writefile test_stack.py\n",
"from nose.tools import assert_equal\n", "from nose.tools import assert_equal\n",
"\n", "\n",
"class Test(object):\n", "\n",
"class TestStack(object):\n",
" \n",
" # TODO: It would be better if we had unit tests for each\n", " # TODO: It would be better if we had unit tests for each\n",
" # method in addition to the following end-to-end test\n", " # method in addition to the following end-to-end test\n",
" def test_end_to_end(self):\n", " def test_end_to_end(self):\n",
@ -233,9 +240,34 @@
" \n", " \n",
" print('Success: test_end_to_end')\n", " print('Success: test_end_to_end')\n",
"\n", "\n",
"def main():\n",
" test = TestStack()\n",
" test.test_end_to_end()\n",
" \n",
"if __name__ == '__main__':\n", "if __name__ == '__main__':\n",
" test = Test()\n", " main()"
" test.test_end_to_end()" ]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Test: Empty stack\n",
"Test: One element\n",
"Test: More than one element\n",
"Success: test_end_to_end\n"
]
}
],
"source": [
"%run -i test_stack.py"
] ]
}, },
{ {

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stacks_queues/stack/test_stack.py Normal file
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from nose.tools import assert_equal
class TestStack(object):
# TODO: It would be better if we had unit tests for each
# method in addition to the following end-to-end test
def test_end_to_end(self):
print('Test: Empty stack')
stack = Stack()
assert_equal(stack.peek(), None)
assert_equal(stack.pop(), None)
print('Test: One element')
top = Node(5)
stack = Stack(top)
assert_equal(stack.pop(), 5)
assert_equal(stack.peek(), None)
print('Test: More than one element')
stack = Stack()
stack.push(1)
stack.push(2)
stack.push(3)
assert_equal(stack.pop(), 3)
assert_equal(stack.peek(), 2)
assert_equal(stack.pop(), 2)
assert_equal(stack.peek(), 1)
assert_equal(stack.is_empty(), False)
assert_equal(stack.pop(), 1)
assert_equal(stack.peek(), None)
assert_equal(stack.is_empty(), True)
print('Success: test_end_to_end')
def main():
test = TestStack()
test.test_end_to_end()
if __name__ == '__main__':
main()