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

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Donne Martin 2015-06-26 05:09:27 -04:00
parent 9490979fe5
commit 585f5b8978
2 changed files with 197 additions and 133 deletions
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313
linked-lists/linked-list.ipynb
View File

@ -13,17 +13,20 @@
"source": [ "source": [
"## Problem: Implement a linked list with insert, append, find, delete, length, and print methods\n", "## Problem: Implement a linked list with insert, append, find, delete, length, and print methods\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",
"* Is this a singly or doubly linked list?\n", "* Is this a singly or doubly linked list?\n",
" * Singly\n", " * Singly\n",
@ -163,11 +166,19 @@
}, },
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 1,
"metadata": { "metadata": {
"collapsed": false "collapsed": false
}, },
"outputs": [], "outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Overwriting linked_list.py\n"
]
}
],
"source": [ "source": [
"%%writefile linked_list.py\n", "%%writefile linked_list.py\n",
"\n", "\n",
@ -200,6 +211,7 @@
" else:\n", " else:\n",
" node.next = self.head\n", " node.next = self.head\n",
" self.head = node\n", " self.head = node\n",
" return node\n",
" \n", " \n",
" def append(self, data, next_node=None):\n", " def append(self, data, next_node=None):\n",
" if data is None:\n", " if data is None:\n",
@ -212,6 +224,7 @@
" while curr_node.next is not None:\n", " while curr_node.next is not None:\n",
" curr_node = curr_node.next\n", " curr_node = curr_node.next\n",
" curr_node.next = node\n", " curr_node.next = node\n",
" return node\n",
" \n", " \n",
" def find(self, data):\n", " def find(self, data):\n",
" if data is None:\n", " if data is None:\n",
@ -224,6 +237,7 @@
" return curr_node\n", " return curr_node\n",
" else:\n", " else:\n",
" curr_node = curr_node.next\n", " curr_node = curr_node.next\n",
" return\n",
" \n", " \n",
" def delete(self, data):\n", " def delete(self, data):\n",
" if data is None:\n", " if data is None:\n",
@ -244,14 +258,22 @@
" curr_node = self.head\n", " curr_node = self.head\n",
" while curr_node is not None:\n", " while curr_node is not None:\n",
" print(curr_node.data)\n", " print(curr_node.data)\n",
" curr_node = curr_node.next" " curr_node = curr_node.next\n",
"\n",
" def get_all_data(self):\n",
" data = []\n",
" curr_node = self.head\n",
" while curr_node is not None:\n",
" data.append(curr_node.data)\n",
" curr_node = curr_node.next\n",
" return data"
] ]
}, },
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 2,
"metadata": { "metadata": {
"collapsed": true "collapsed": false
}, },
"outputs": [], "outputs": [],
"source": [ "source": [
@ -259,139 +281,170 @@
] ]
}, },
{ {
"cell_type": "code", "cell_type": "markdown",
"execution_count": null, "metadata": {},
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [ "source": [
"# Test insert_to_front\n", "## Unit Test"
"# Insert in an empty list\n", ]
"linked_list = LinkedList(None)\n", },
"linked_list.insert_to_front(10)\n", {
"linked_list.print_list()\n", "cell_type": "markdown",
"# Insert a NULL\n", "metadata": {},
"linked_list.insert_to_front(None)\n", "source": [
"linked_list.print_list()\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.*"
"# Insert in a list with one element or more elements\n",
"linked_list.insert_to_front('a')\n",
"linked_list.insert_to_front('bc')\n",
"linked_list.print_list()"
] ]
}, },
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 3,
"metadata": { "metadata": {
"collapsed": false "collapsed": false
}, },
"outputs": [], "outputs": [
"source": [
"# Test append\n",
"# Insert in an empty list\n",
"linked_list = LinkedList(None)\n",
"linked_list.append(10)\n",
"linked_list.print_list()\n",
"# Insert a NULL\n",
"linked_list.append(None)\n",
"linked_list.print_list()\n",
"# Insert in a list with one element or more elements\n",
"linked_list.append('a')\n",
"linked_list.append('bc')\n",
"linked_list.print_list()"
]
},
{ {
"cell_type": "code", "name": "stdout",
"execution_count": null, "output_type": "stream",
"metadata": { "text": [
"collapsed": false "Test: insert_to_front on an empty list\n",
}, "Test: insert_to_front on a NULL\n",
"outputs": [], "Test: insert_to_front general case\n",
"source": [ "Success: test_insert_to_front\n",
"# Test find\n", "\n",
"# Find in an empty list\n", "Test: append on an empty list\n",
"linked_list = LinkedList(None)\n", "Test: append a NULL\n",
"node = linked_list.find('a')\n", "Test: append general case\n",
"print(node)\n", "Success: test_append\n",
"# Find a NULL\n", "\n",
"head = Node(10)\n", "Test: find on an empty list\n",
"linked_list = LinkedList(head)\n", "Test: find a NULL\n",
"node = linked_list.find(None)\n", "Test: find general case with matches\n",
"print(node)\n", "Test: find general case with no matches\n",
"# Find in a list with one element or more matching elements\n", "Success: test_find\n",
"head = Node(10)\n", "\n",
"linked_list = LinkedList(head)\n", "Test: delete on an empty list\n",
"linked_list.insert_to_front('a')\n", "Test: delete a NULL\n",
"linked_list.insert_to_front('bc')\n", "Test: delete general case with matches\n",
"node = linked_list.find('a')\n", "Test: delete general case with no matches\n",
"print(node)\n", "Success: test_delete\n",
"# Find in a list with no matches\n", "\n",
"node = linked_list.find('aaa')\n", "Test: len on an empty list\n",
"print(node)" "Test: len general case\n",
"Success: test_len\n",
"\n"
] ]
}, }
{ ],
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [ "source": [
"# Test delete\n", "from nose.tools import assert_equal\n",
"# Delete in an empty list\n", "\n",
"linked_list = LinkedList(None)\n", "class Test(object):\n",
"linked_list.delete('a')\n", " def test_insert_to_front(self):\n",
"linked_list.print_list()\n", " print('Test: insert_to_front on an empty list')\n",
"# Delete a NULL\n", " linked_list = LinkedList(None)\n",
"head = Node(10)\n", " linked_list.insert_to_front(10)\n",
"linked_list = LinkedList(head)\n", " assert_equal(linked_list.get_all_data(), [10])\n",
"linked_list.delete(None)\n", "\n",
"linked_list.print_list()\n", " print('Test: insert_to_front on a NULL')\n",
"# Delete in a list with one element or more matching elements\n", " linked_list.insert_to_front(None)\n",
"head = Node(10)\n", " assert_equal(linked_list.get_all_data(), [10])\n",
"linked_list = LinkedList(head)\n", "\n",
"linked_list.insert_to_front('a')\n", " print('Test: insert_to_front general case')\n",
"linked_list.insert_to_front('bc')\n", " linked_list.insert_to_front('a')\n",
"linked_list.delete('a')\n", " linked_list.insert_to_front('bc')\n",
"linked_list.print_list()\n", " assert_equal(linked_list.get_all_data(), ['bc', 'a', 10])\n",
"# Delete in a list with no matches\n", " \n",
"linked_list.delete('aa')" " print('Success: test_insert_to_front\\n')\n",
] " \n",
}, " def test_append(self):\n",
{ " print('Test: append on an empty list')\n",
"cell_type": "code", " linked_list = LinkedList(None)\n",
"execution_count": null, " linked_list.append(10)\n",
"metadata": { " assert_equal(linked_list.get_all_data(), [10])\n",
"collapsed": false "\n",
}, " print('Test: append a NULL')\n",
"outputs": [], " linked_list.append(None)\n",
"source": [ " assert_equal(linked_list.get_all_data(), [10])\n",
"# Test length\n", "\n",
"# Zero elements\n", " print('Test: append general case')\n",
"linked_list = LinkedList(None)\n", " linked_list.append('a')\n",
"print(len(linked_list))\n", " linked_list.append('bc')\n",
"# One or more elements\n", " assert_equal(linked_list.get_all_data(), [10, 'a', 'bc'])\n",
"head = Node(10)\n", " \n",
"linked_list = LinkedList(head)\n", " print('Success: test_append\\n')\n",
"linked_list.insert_to_front('a')\n", " \n",
"linked_list.insert_to_front('bc')\n", " def test_find(self):\n",
"print(len(linked_list))" " print('Test: find on an empty list')\n",
] " linked_list = LinkedList(None)\n",
}, " node = linked_list.find('a')\n",
{ " assert_equal(node, None)\n",
"cell_type": "code", "\n",
"execution_count": null, " print('Test: find a NULL')\n",
"metadata": { " head = Node(10)\n",
"collapsed": false " linked_list = LinkedList(head)\n",
}, " node = linked_list.find(None)\n",
"outputs": [], " assert_equal(node, None)\n",
"source": [ "\n",
"# Test empty print\n", " print('Test: find general case with matches')\n",
"linked_list = LinkedList(None)\n", " head = Node(10)\n",
"linked_list.print_list()" " linked_list = LinkedList(head)\n",
" linked_list.insert_to_front('a')\n",
" linked_list.insert_to_front('bc')\n",
" node = linked_list.find('a')\n",
" assert_equal(str(node), 'a')\n",
"\n",
" print('Test: find general case with no matches')\n",
" node = linked_list.find('aaa')\n",
" assert_equal(node, None)\n",
" \n",
" print('Success: test_find\\n')\n",
" \n",
" def test_delete(self):\n",
" print('Test: delete on an empty list')\n",
" linked_list = LinkedList(None)\n",
" linked_list.delete('a')\n",
" assert_equal(linked_list.get_all_data(), [])\n",
"\n",
" print('Test: delete a NULL')\n",
" head = Node(10)\n",
" linked_list = LinkedList(head)\n",
" linked_list.delete(None)\n",
" assert_equal(linked_list.get_all_data(), [10])\n",
"\n",
" print('Test: delete general case with matches')\n",
" head = Node(10)\n",
" linked_list = LinkedList(head)\n",
" linked_list.insert_to_front('a')\n",
" linked_list.insert_to_front('bc')\n",
" linked_list.delete('a')\n",
" assert_equal(linked_list.get_all_data(), ['bc', 10])\n",
"\n",
" print('Test: delete general case with no matches')\n",
" linked_list.delete('aa')\n",
" assert_equal(linked_list.get_all_data(), ['bc', 10])\n",
" \n",
" print('Success: test_delete\\n')\n",
" \n",
" def test_len(self):\n",
" print('Test: len on an empty list')\n",
" linked_list = LinkedList(None)\n",
" assert_equal(len(linked_list), 0)\n",
"\n",
" print('Test: len general case')\n",
" head = Node(10)\n",
" linked_list = LinkedList(head)\n",
" linked_list.insert_to_front('a')\n",
" linked_list.insert_to_front('bc')\n",
" assert_equal(len(linked_list), 3)\n",
" \n",
" print('Success: test_len\\n')\n",
"\n",
"if __name__ == '__main__':\n",
" test = Test()\n",
" test.test_insert_to_front()\n",
" test.test_append()\n",
" test.test_find()\n",
" test.test_delete()\n",
" test.test_len()"
] ]
} }
], ],

11
linked-lists/linked_list.py
View File

@ -28,6 +28,7 @@ class LinkedList(object):
else: else:
node.next = self.head node.next = self.head
self.head = node self.head = node
return node
def append(self, data, next_node=None): def append(self, data, next_node=None):
if data is None: if data is None:
@ -40,6 +41,7 @@ class LinkedList(object):
while curr_node.next is not None: while curr_node.next is not None:
curr_node = curr_node.next curr_node = curr_node.next
curr_node.next = node curr_node.next = node
return node
def find(self, data): def find(self, data):
if data is None: if data is None:
@ -52,6 +54,7 @@ class LinkedList(object):
return curr_node return curr_node
else: else:
curr_node = curr_node.next curr_node = curr_node.next
return
def delete(self, data): def delete(self, data):
if data is None: if data is None:
@ -73,3 +76,11 @@ class LinkedList(object):
while curr_node is not None: while curr_node is not None:
print(curr_node.data) print(curr_node.data)
curr_node = curr_node.next curr_node = curr_node.next
def get_all_data(self):
data = []
curr_node = self.head
while curr_node is not None:
data.append(curr_node.data)
curr_node = curr_node.next
return data