{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "This notebook was prepared by Marco Guajardo. Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# Challenge Notebook" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Problem: Implement a binary search tree with insert, delete, different traversals & max/min node values\n", "* [Constraints](#Constraints)\n", "* [Test Cases](#Test-Cases)\n", "* [Algorithm](#Algorithm)\n", "* [Code](#Code)\n", "* [Unit Test](#Unit-Test)\n", "* [Solution Notebook](#Solution-Notebook)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Constraints\n", "* Is this a binary tree?\n", " * Yes\n", "* Is the root set to None initially?\n", " * Yes\n", "* Do we care if the tree is balanced?\n", " * No\n", "* What do we return for the traversals?\n", " * Return a list of the data in the desired order\n", "* What type of data can the tree hold?\n", " * Assume the tree only takes ints. In a realistic example, we'd use a hash table to convert other types to ints." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Test Cases\n", "\n", "### Insert \n", "\n", "* Always start with the root\n", "* If value is less than the root, go to the left child\n", "* if value is more than the root, go to the right child\n", "\n", "\n", "### Delete\n", "\n", "* Deleting a node from a binary tree is tricky. Make sure you arrange the tree correctly when deleting a node.\n", "* Here are some basic [instructions](http://www.algolist.net/Data_structures/Binary_search_tree/Removal)\n", "* If the value to delete isn't on the tree return False\n", "\n", "### Traverals \n", "\n", "* In order traversal -left, center, right\n", "* Pre order traversal - center, left, right\n", "* Post order traversal - left, right, center\n", "* Return list for all traverals \n", "\n", "### Max & Min\n", "* Find the max node in the binary search tree\n", "* Find the min node in the binary search tree\n", "\n", "### treeIsEmpty\n", "* check if the tree is empty\n", "\n", "\n", "## Algorithm\n", "\n", "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/binary_tree_implementation/binary_tree_solution.ipynb). If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Code" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "class Node (object):\n", " def __init__ (self, data=None):\n", " #TODO:implement me\n", " pass\n", " \n", " def __str__ (self):\n", " #TODO:implement me\n", " pass" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "class BinaryTree (object):\n", " def __init__ (self):\n", " #TODO:implement me\n", " pass\n", " \n", " def insert (self, newData):\n", " #TODO:implement me\n", " pass\n", " \n", " def delete (self, key):\n", " #TODO:implement me\n", " pass\n", " \n", " def maxNode (self):\n", " #TODO:implement me\n", " pass\n", " \n", " def minNode (self):\n", " #TODO:implement me\n", " pass\n", " \n", " def printPostOrder (self):\n", " #TODO:implement me\n", " pass\n", " \n", " def printPreOrder (self):\n", " #TODO:implement me\n", " pass\n", " \n", " def printInOrder (self):\n", " #TODO:implement me\n", " pass\n", " \n", " def treeIsEmpty (self):\n", " #TODO: implement me\n", " pass\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Unit Test" ] }, { "cell_type": "code", "execution_count": 6, "metadata": { "collapsed": false }, "outputs": [], "source": [ "from nose.tools import assert_equal\n", "\n", "class TestBinaryTree(object):\n", "\n", "\tdef test_insert_traversals (self):\n", "\t\tmyTree = BinaryTree()\n", "\t\tmyTree2 = BinaryTree()\n", "\t\tfor num in [50, 30, 70, 10, 40, 60, 80, 7, 25, 38]:\n", "\t\t\tmyTree.insert(num)\n", "\t\t[myTree2.insert(num) for num in range (1, 100, 10)]\n", "\n", "\t\tprint(\"Test: insert checking with in order traversal\")\n", "\t\texpectVal = [7, 10, 25, 30, 38, 40, 50, 60, 70, 80]\n", "\t\tassert_equal(myTree.printInOrder(), expectVal)\n", "\t\texpectVal = [1, 11, 21, 31, 41, 51, 61, 71, 81, 91]\n", "\t\tassert_equal(myTree2.printInOrder(), expectVal)\n", "\n", "\t\tprint(\"Test: insert checking with post order traversal\")\n", "\t\texpectVal = [7, 25, 10, 38, 40, 30, 60, 80, 70, 50]\n", "\t\tassert_equal(myTree.printPostOrder(), expectVal)\n", "\t\texpectVal = [91, 81, 71, 61, 51, 41, 31, 21, 11, 1]\n", "\t\tassert_equal(myTree2.printPostOrder(), expectVal)\n", "\n", "\n", "\t\tprint(\"Test: insert checking with pre order traversal\")\n", "\t\texpectVal = [50, 30, 10, 7, 25, 40, 38, 70, 60, 80]\n", "\t\tassert_equal(myTree.printPreOrder(), expectVal)\n", "\t\texpectVal = [1, 11, 21, 31, 41, 51, 61, 71, 81, 91]\n", "\t\tassert_equal(myTree2.printPreOrder(), expectVal)\n", "\n", "\n", "\t\tprint(\"Success: test_insert_traversals\")\n", "\n", "\tdef test_max_min_nodes (self):\n", "\t\tmyTree = BinaryTree()\n", "\t\tmyTree.insert(5)\n", "\t\tmyTree.insert(1)\n", "\t\tmyTree.insert(21)\n", "\n", "\t\tprint(\"Test: max node\")\n", "\t\tassert_equal(myTree.maxNode(), 21)\n", "\t\tmyTree.insert(32)\n", "\t\tassert_equal(myTree.maxNode(), 32)\n", "\n", "\t\tprint(\"Test: min node\")\n", "\t\tassert_equal(myTree.minNode(), 1)\n", "\n", "\t\tprint(\"Test: min node inserting negative number\")\n", "\t\tmyTree.insert(-10)\n", "\t\tassert_equal(myTree.minNode(), -10)\n", "\n", "\t\tprint(\"Success: test_max_min_nodes\")\n", "\n", "\tdef test_delete (self):\n", "\t\tmyTree = BinaryTree()\n", "\t\tmyTree.insert(5)\n", "\n", "\t\tprint(\"Test: delete\")\n", "\t\tmyTree.delete(5)\n", "\t\tassert_equal(myTree.treeIsEmpty(), True)\n", "\t\t\n", "\t\tprint(\"Test: more complex deletions\")\n", "\t\t[myTree.insert(x) for x in range(1, 5)]\n", "\t\tmyTree.delete(2)\n", "\t\tassert_equal(myTree.root.rightChild.data, 3)\n", " \n", "\t\tprint(\"Test: delete invalid value\")\n", "\t\tassert_equal(myTree.delete(100), False)\n", "\n", "\n", "\t\tprint(\"Success: test_delete\")\n", "\n", "def main():\n", " testing = TestBinaryTree()\n", " testing.test_insert_traversals()\n", " testing.test_max_min_nodes()\n", " testing.test_delete()\n", " \n", "if __name__=='__main__':\n", " main()" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**The following unit test is expected to fail until you solve the challenge.**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Solution NoteBook\n", "\n", "Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/binary_tree_implementation/binary_tree_solution.ipynb) for a discussion on algorithms and code solutions." ] } ], "metadata": { "kernelspec": { "display_name": "Python 3", "language": "python", "name": "python3" }, "language_info": { "codemirror_mode": { "name": "ipython", "version": 3 }, "file_extension": ".py", "mimetype": "text/x-python", "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython3", "version": "3.4.3" } }, "nbformat": 4, "nbformat_minor": 0 }