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

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Donne Martin 2015-06-27 06:32:01 -04:00
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commit 582e3c0181
1 changed files with 79 additions and 42 deletions
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109
stacks-queues/n-stacks.ipynb
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@ -13,17 +13,20 @@
"source": [ "source": [
"## Problem: Implement n stacks using a single array.\n", "## Problem: Implement n stacks using a single array.\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",
"*Problem statements are often intentionally ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
"\n", "\n",
"* Are the stacks and array a fixed size?\n", "* Are the stacks and array a fixed size?\n",
" * Yes" " * Yes"
@ -48,8 +51,13 @@
"source": [ "source": [
"## Algorithm\n", "## Algorithm\n",
"\n", "\n",
"* Initialize array\n", "### Absolute Index\n",
"* Initialize stack pointers to -1\n", "\n",
"* return stack size * stack index + stack pointer\n",
"\n",
"Complexity:\n",
"* Time: O(1)\n",
"* Space: O(1)\n",
"\n", "\n",
"### Push\n", "### Push\n",
"\n", "\n",
@ -74,15 +82,6 @@
"\n", "\n",
"Complexity:\n", "Complexity:\n",
"* Time: O(1)\n", "* Time: O(1)\n",
"* Space: O(1)\n",
"\n",
"\n",
"### Absolute Index\n",
"\n",
"* return stack size * stack index + stack pointer\n",
"\n",
"Complexity:\n",
"* Time: O(1)\n",
"* Space: O(1)" "* Space: O(1)"
] ]
}, },
@ -95,7 +94,7 @@
}, },
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 1,
"metadata": { "metadata": {
"collapsed": true "collapsed": true
}, },
@ -130,39 +129,77 @@
" 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": 2,
"metadata": { "metadata": {
"collapsed": false "collapsed": false
}, },
"outputs": [], "outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Test: Pop on empty stack\n",
"Test: Push to full stack\n",
"Test: Push to non-full stack\n",
"Test: Pop on non-empty stack\n",
"Success: test_stacks\n",
"\n"
]
}
],
"source": [ "source": [
"num_stacks = 3\n", "from nose.tools import assert_equal\n",
"stack_size = 100\n", "from nose.tools import raises\n",
"print('Pop on empty stack')\n", "\n",
"class Test(object):\n",
" @raises(Exception)\n",
" def test_pop_on_empty(self, num_stacks, stack_size):\n",
" print('Test: Pop on empty stack')\n",
" stacks = Stacks(num_stacks, stack_size)\n", " stacks = Stacks(num_stacks, stack_size)\n",
"try:\n",
" stacks.pop(0)\n", " stacks.pop(0)\n",
"except Exception as e:\n", "\n",
" print(e)\n", " @raises(Exception)\n",
"print('Push to non-full stack')\n", " def test_push_on_full(self, num_stacks, stack_size):\n",
" print('Test: Push to full stack')\n",
" stacks = Stacks(num_stacks, stack_size)\n",
" for i in xrange(0, stack_size):\n",
" stacks.push(2, i)\n",
" stacks.push(2, stack_size)\n",
"\n",
" def test_stacks(self, num_stacks, stack_size):\n",
" print('Test: Push to non-full stack')\n",
" stacks = Stacks(num_stacks, stack_size)\n",
" stacks.push(0, 1)\n", " stacks.push(0, 1)\n",
" stacks.push(0, 2)\n", " stacks.push(0, 2)\n",
" stacks.push(1, 3)\n", " stacks.push(1, 3)\n",
" stacks.push(2, 4)\n", " stacks.push(2, 4)\n",
"print('Pop on non-empty stack')\n", "\n",
"print(stacks.pop(0))\n", " print('Test: Pop on non-empty stack')\n",
"print(stacks.pop(0))\n", " assert_equal(stacks.pop(0), 2)\n",
"print(stacks.pop(1))\n", " assert_equal(stacks.pop(0), 1)\n",
"print(stacks.pop(2))\n", " assert_equal(stacks.pop(1), 3)\n",
"print('Push to full stack')\n", " assert_equal(stacks.pop(2), 4)\n",
"for i in xrange(0, stack_size):\n", "\n",
" stacks.push(2, i)\n", " print('Success: test_stacks\\n')\n",
"try:\n", "\n",
" stacks.push(2, stack_size)\n", "if __name__ == '__main__':\n",
"except Exception as e:\n", " num_stacks = 3\n",
" print(e)" " stack_size = 100 \n",
" test = Test()\n",
" test.test_pop_on_empty(num_stacks, stack_size)\n",
" test.test_push_on_full(num_stacks, stack_size)\n",
" test.test_stacks(num_stacks, stack_size)"
] ]
} }
], ],