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Reworked notebook: Added more detail to constraints and test cases. Reworked unit test.

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Donne Martin 2015-06-27 06:34:57 -04:00
parent 8c93b51fc6
commit 5719b04c10
1 changed files with 71 additions and 26 deletions
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97
stacks-queues/stack-min.ipynb
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@ -13,19 +13,24 @@
"source": [ "source": [
"## Problem: Implement a stack with push, pop, and min methods running O(1) time.\n", "## Problem: Implement a stack with push, pop, and min methods running O(1) time.\n",
"\n", "\n",
"* [Clarifying Questions](#Clarifying-Questions)\n", "* [Constraints and Assumptions](#Constraints-and-Assumptions)\n",
"* [Test Cases](#Test-Cases)\n", "* [Test Cases](#Test-Cases)\n",
"* [Algorithm](#Algorithm)\n", "* [Algorithm](#Algorithm)\n",
"* [Code](#Code)" "* [Code](#Code)\n",
"* [Unit Test](#Unit-Test)"
] ]
}, },
{ {
"cell_type": "markdown", "cell_type": "markdown",
"metadata": {}, "metadata": {},
"source": [ "source": [
"## Clarifying Questions\n", "## Constraints and Assumptions\n",
"\n", "\n",
"* Is this a stack of ints?\n", "*Problem statements are often intentionally ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
"\n",
"* Can we assume this is a stack of ints?\n",
" * Yes\n",
"* Can we assume we already have a stack class that can be used for this problem?\n",
" * Yes" " * Yes"
] ]
}, },
@ -49,7 +54,7 @@
"\n", "\n",
"### Min\n", "### Min\n",
"\n", "\n",
"* If the second stack is empty, return the max int value\n", "* If the second stack is empty, return an error code (max int value)\n",
"* Else, return the top of the stack, without popping it\n", "* Else, return the top of the stack, without popping it\n",
"\n", "\n",
"Complexity:\n", "Complexity:\n",
@ -87,7 +92,7 @@
}, },
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 1,
"metadata": { "metadata": {
"collapsed": true "collapsed": true
}, },
@ -98,7 +103,7 @@
}, },
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 2,
"metadata": { "metadata": {
"collapsed": true "collapsed": true
}, },
@ -129,31 +134,71 @@
" return data" " return data"
] ]
}, },
{
"cell_type": "markdown",
"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.*"
]
},
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 3,
"metadata": { "metadata": {
"collapsed": false "collapsed": false
}, },
"outputs": [], "outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Test: Push on empty stack, non-empty stack\n",
"Test: Pop on non-empty stack\n",
"Test: Pop empty stack\n",
"Success: test_stack_min\n"
]
}
],
"source": [ "source": [
"print('Push on empty stack, non-empty stack')\n", "from nose.tools import assert_equal\n",
"stack = MyStack()\n", "\n",
"stack.push(5)\n", "class Test(object):\n",
"print('Push:', stack.peek(), 'Min after push:', stack.min())\n", " def test_stack_min(self):\n",
"stack.push(1)\n", " print('Test: Push on empty stack, non-empty stack')\n",
"print('Push:', stack.peek(), 'Min after push:', stack.min())\n", " stack = MyStack()\n",
"stack.push(3)\n", " stack.push(5)\n",
"print('Push:', stack.peek(), 'Min after push:', stack.min())\n", " assert_equal(stack.peek(), 5)\n",
"stack.push(0)\n", " assert_equal(stack.min(), 5)\n",
"print('Push:', stack.peek(), 'Min after push:', stack.min())\n", " stack.push(1)\n",
"print('Pop on non-empty stack')\n", " assert_equal(stack.peek(), 1)\n",
"print('Pop:', stack.pop(), 'Min after pop:', stack.min())\n", " assert_equal(stack.min(), 1)\n",
"print('Pop:', stack.pop(), 'Min after pop:', stack.min())\n", " stack.push(3)\n",
"print('Pop:', stack.pop(), 'Min after pop:', stack.min())\n", " assert_equal(stack.peek(), 3)\n",
"print('Pop:', stack.pop(), 'Min after pop:', stack.min())\n", " assert_equal(stack.min(), 1)\n",
"print('Stack contents:', stack.peek())\n", " stack.push(0)\n",
"print('Pop empty stack:', stack.pop())" " assert_equal(stack.peek(), 0)\n",
" assert_equal(stack.min(), 0)\n",
"\n",
" print('Test: Pop on non-empty stack')\n",
" assert_equal(stack.pop(), 0)\n",
" assert_equal(stack.min(), 1)\n",
" assert_equal(stack.pop(), 3)\n",
" assert_equal(stack.min(), 1)\n",
" assert_equal(stack.pop(), 1)\n",
" assert_equal(stack.min(), 5)\n",
" assert_equal(stack.pop(), 5)\n",
" assert_equal(stack.min(), sys.maxint)\n",
"\n",
" print('Test: Pop empty stack')\n",
" assert_equal(stack.pop(), None)\n",
" \n",
" print('Success: test_stack_min')\n",
"\n",
"if __name__ == '__main__':\n",
" test = Test()\n",
" test.test_stack_min()"
] ]
} }
], ],