diff --git a/linked-lists/partition.ipynb b/linked-lists/partition.ipynb index 9496114..90b9336 100644 --- a/linked-lists/partition.ipynb +++ b/linked-lists/partition.ipynb @@ -13,21 +13,28 @@ "source": [ "## Problem: Partition a linked list around a value x, such that all nodes less than x come before all nodes greater than or equal to x.\n", "\n", - "* [Clarifying Questions](#Clarifying-Questions)\n", + "* [Constraints and Assumptions](#Constraints-and-Assumptions)\n", "* [Test Cases](#Test-Cases)\n", "* [Algorithm](#Algorithm)\n", - "* [Code](#Code)" + "* [Code](#Code)\n", + "* [Unit Test](#Unit-Test)" ] }, { "cell_type": "markdown", "metadata": {}, "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", "* Can we create additional data structures?\n", " * Yes\n", "* Do you expect the function to return a new list?\n", + " * Yes\n", + "* Can we assume the input x is valid?\n", + " * Yes\n", + "* Can we assume we already have a linked list class that can be used for this problem?\n", " * Yes" ] }, @@ -41,7 +48,6 @@ "* One element list\n", "* Left linked list is empty\n", "* Right linked list is empty\n", - "* X invalid\n", "* General case\n", " * Partition = 10\n", " * Input: 4, 3, 7, 8, 10, 1, 10, 12\n", @@ -54,7 +60,6 @@ "source": [ "## Algorithm\n", "\n", - "* Test error cases\n", "* Create left and right linked lists\n", "* For each element in the list\n", " * If elem < x, append to the left list\n", @@ -75,7 +80,7 @@ }, { "cell_type": "code", - "execution_count": null, + "execution_count": 1, "metadata": { "collapsed": true }, @@ -86,9 +91,9 @@ }, { "cell_type": "code", - "execution_count": null, + "execution_count": 2, "metadata": { - "collapsed": true + "collapsed": false }, "outputs": [], "source": [ @@ -96,11 +101,11 @@ " def partition(self, data):\n", " if self.head is None:\n", " return\n", - " if type(data) != int:\n", - " raise ValueError('Invalid int argument: data')\n", " left = MyLinkedList(None)\n", " right = MyLinkedList(None)\n", " curr = self.head\n", + " \n", + " # Build the left and right lists\n", " while curr is not None:\n", " if curr.data < data:\n", " left.append(curr.data)\n", @@ -111,52 +116,87 @@ " if curr_left is None:\n", " return right\n", " else:\n", + " # Merge the two lists\n", " while curr_left.next is not None:\n", " curr_left = curr_left.next\n", " curr_left.next = right.head\n", " return left" ] }, + { + "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", - "execution_count": null, + "execution_count": 3, "metadata": { "collapsed": false }, - "outputs": [], + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "Test: Empty list\n", + "Test: One element list, left list empty\n", + "Test: Right list is empty\n", + "Test: General case\n", + "Success: test_partition\n" + ] + } + ], "source": [ - "print('Empty list')\n", - "linked_list = MyLinkedList(None)\n", - "linked_list.partition(10)\n", - "linked_list.print_list()\n", - "print('X invalid')\n", - "head = Node(12)\n", - "linked_list = MyLinkedList(head)\n", - "try:\n", - " linked_list.partition('a')\n", - "except ValueError as err:\n", - " print(err)\n", - "linked_list.print_list()\n", - "print('One element list')\n", - "print('Left linked list is empty')\n", - "linked_list.partition(1)\n", - "linked_list.print_list()\n", - "print('Right linked list is empty')\n", - "linked_list.partition(20)\n", - "linked_list.print_list()\n", - "print('General case')\n", - "# Partition = 10\n", - "# Input 4, 3, 7, 8, 10, 1, 10, 12\n", - "# Output 4, 3, 7, 8, 1, 10, 10, 12\n", - "linked_list.insert_to_front(10)\n", - "linked_list.insert_to_front(1)\n", - "linked_list.insert_to_front(10)\n", - "linked_list.insert_to_front(8)\n", - "linked_list.insert_to_front(7)\n", - "linked_list.insert_to_front(3)\n", - "linked_list.insert_to_front(4)\n", - "partitioned_list = linked_list.partition(10)\n", - "partitioned_list.print_list()" + "from nose.tools import assert_equal\n", + "\n", + "class Test(object):\n", + " def test_partition(self):\n", + " print('Test: Empty list')\n", + " linked_list = MyLinkedList(None)\n", + " linked_list.partition(10)\n", + " assert_equal(linked_list.get_all_data(), [])\n", + "\n", + " print('Test: One element list, left list empty')\n", + " linked_list = MyLinkedList(Node(5))\n", + " linked_list.partition(0)\n", + " assert_equal(linked_list.get_all_data(), [5])\n", + "\n", + " print('Test: Right list is empty')\n", + " linked_list = MyLinkedList(Node(5))\n", + " linked_list.partition(10)\n", + " assert_equal(linked_list.get_all_data(), [5])\n", + "\n", + " print('Test: General case')\n", + " # Partition = 10\n", + " # Input: 4, 3, 7, 8, 10, 1, 10, 12\n", + " # Output: 4, 3, 7, 8, 1, 10, 10, 12\n", + " linked_list = MyLinkedList(Node(12))\n", + " linked_list.insert_to_front(10)\n", + " linked_list.insert_to_front(1)\n", + " linked_list.insert_to_front(10)\n", + " linked_list.insert_to_front(8)\n", + " linked_list.insert_to_front(7)\n", + " linked_list.insert_to_front(3)\n", + " linked_list.insert_to_front(4)\n", + " partitioned_list = linked_list.partition(10)\n", + " assert_equal(partitioned_list.get_all_data(), \n", + " [4, 3, 7, 8, 1, 10, 10, 12])\n", + " \n", + " print('Success: test_partition')\n", + "\n", + "if __name__ == '__main__':\n", + " test = Test()\n", + " test.test_partition()" ] } ],