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

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Donne Martin 2015-06-26 05:05:36 -04:00
parent 27ebbf6581
commit 5a93da3dda
1 changed files with 73 additions and 30 deletions
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103
linked-lists/delete-mid.ipynb
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@ -13,20 +13,25 @@
"source": [ "source": [
"## Problem: Delete a node in the middle, given only access to that node.\n", "## Problem: Delete a node in the middle, given only access to that node.\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",
"* What if the final node is being deleted, for example a single node list?\n", "*Problem statements are often intentionally ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
" * Make it a dummy node" "\n",
"* What if the final node is being deleted, for example a single node list? Do we make it a dummy with a NULL value?\n",
" * Yes\n",
"* Can we assume we already have a linked list class that can be used for this problem?\n",
" * Yes"
] ]
}, },
{ {
@ -67,7 +72,7 @@
}, },
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 1,
"metadata": { "metadata": {
"collapsed": true "collapsed": true
}, },
@ -78,9 +83,9 @@
}, },
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 2,
"metadata": { "metadata": {
"collapsed": true "collapsed": false
}, },
"outputs": [], "outputs": [],
"source": [ "source": [
@ -95,39 +100,77 @@
" return\n", " return\n",
" if node is None:\n", " if node is None:\n",
" return\n", " return\n",
" next = node.next\n", " node_next = node.next\n",
" if next is None:\n", " if node_next is None:\n",
" node.data = None\n", " node.data = None\n",
" node.next = None\n", " node.next = None\n",
" else:\n", " else:\n",
" node.data = next.data\n", " node.data = node_next.data\n",
" node.next = next.next" " node.next = node_next.next"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## 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", "cell_type": "code",
"execution_count": null, "execution_count": 3,
"metadata": { "metadata": {
"collapsed": false "collapsed": false
}, },
"outputs": [], "outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Test: Empty list, null node to delete\n",
"Test: One node\n",
"Test: Multiple nodes\n",
"Success: test_delete_node\n"
]
}
],
"source": [ "source": [
"# Empty list\n", "from nose.tools import assert_equal\n",
"linked_list = LinkedList(None)\n", "\n",
"linked_list.delete_node(None)\n", "class Test(object):\n",
"linked_list.print_list()\n", " def test_delete_node(self):\n",
"# One node\n", " print('Test: Empty list, null node to delete')\n",
"head = Node(2)\n", " linked_list = MyLinkedList(None)\n",
"linked_list = LinkedList(head)\n", " linked_list.delete_node(None)\n",
"linked_list.delete_node(head)\n", " assert_equal(linked_list.get_all_data(), [])\n",
"linked_list.print_list()\n", "\n",
"# Multiple nodes\n", " print('Test: One node')\n",
"node0 = linked_list.insert_to_front(1)\n", " head = Node(2)\n",
"node1 = linked_list.insert_to_front(3)\n", " linked_list = MyLinkedList(head)\n",
"node2 = linked_list.insert_to_front(4)\n", " linked_list.delete_node(head)\n",
"node3 = linked_list.insert_to_front(1)\n", " assert_equal(linked_list.get_all_data(), [None])\n",
"linked_list.delete_node(node2)\n", "\n",
"linked_list.print_list()" " print('Test: Multiple nodes')\n",
" linked_list = MyLinkedList(None) \n",
" node0 = linked_list.insert_to_front(1)\n",
" node1 = linked_list.insert_to_front(3)\n",
" node2 = linked_list.insert_to_front(4)\n",
" node3 = linked_list.insert_to_front(1)\n",
" linked_list.delete_node(node2)\n",
" assert_equal(linked_list.get_all_data(), [1, 3, 1])\n",
" \n",
" print('Success: test_delete_node')\n",
"\n",
"if __name__ == '__main__':\n",
" test = Test()\n",
" test.test_delete_node()"
] ]
} }
], ],