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https://github.com/donnemartin/interactive-coding-challenges.git
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Add bst second largest challenge
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Donne Martin
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commit
6c507fc3ea
0
graphs_trees/bst_second_largest/__init__.py
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0
graphs_trees/bst_second_largest/__init__.py
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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Challenge Notebook"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Problem: Find the second largest node in a binary search tree.\n",
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"\n",
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"* [Constraints](#Constraints)\n",
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"* [Test Cases](#Test-Cases)\n",
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"* [Algorithm](#Algorithm)\n",
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"* [Code](#Code)\n",
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"* [Unit Test](#Unit-Test)\n",
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"* [Solution Notebook](#Solution-Notebook)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Constraints\n",
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"\n",
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"* If this is called on a None input or a single node, should we raise an exception?\n",
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" * Yes\n",
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" * None -> TypeError\n",
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" * Single node -> ValueError\n",
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"* Can we assume we already have a Node class with an insert method?\n",
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" * Yes\n",
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"* Can we assume this fits memory?\n",
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" * Yes"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Test Cases\n",
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"\n",
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"* None or single node -> Exception\n",
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"\n",
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"<pre>\n",
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"Input:\n",
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" _10_\n",
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" _/ \\_ \n",
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" 5 15\n",
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" / \\ / \\\n",
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" 3 8 12 20\n",
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" / \\ \\\n",
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" 2 4 30\n",
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"\n",
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"Output: 20\n",
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"\n",
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"Input:\n",
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" 10\n",
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" / \n",
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" 5\n",
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" / \\\n",
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" 3 7\n",
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"Output: 7\n",
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"</pre>"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Algorithm\n",
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"\n",
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"Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/check_balance/check_balance_solution.ipynb). If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Code"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"%run ../bst/bst.py\n",
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"%load ../bst/bst.py"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"class Solution(Bst):\n",
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"\n",
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" def find_second_largest(self):\n",
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" # TODO: Implement me\n",
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" pass"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Unit Test"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"**The following unit test is expected to fail until you solve the challenge.**"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"# %load test_bst_second_largest.py\n",
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"from nose.tools import assert_equal, assert_raises\n",
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"\n",
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"\n",
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"class TestBstSecondLargest(object):\n",
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"\n",
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" def test_bst_second_largest(self):\n",
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" bst = Solution(None)\n",
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" assert_raises(TypeError, bst.find_second_largest)\n",
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" root = Node(10)\n",
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" bst = Solution(root)\n",
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" node5 = bst.insert(5)\n",
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" node15 = bst.insert(15)\n",
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" node3 = bst.insert(3)\n",
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" node8 = bst.insert(8)\n",
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" node12 = bst.insert(12)\n",
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" node20 = bst.insert(20)\n",
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" node2 = bst.insert(2)\n",
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" node4 = bst.insert(4)\n",
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" node30 = bst.insert(30)\n",
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" assert_equal(bst.find_second_largest(), node20)\n",
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" root = Node(10)\n",
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" bst = Solution(root)\n",
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" node5 = bst.insert(5)\n",
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" node3 = bst.insert(3)\n",
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" node7 = bst.insert(7)\n",
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" assert_equal(bst.find_second_largest(), node7)\n",
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" print('Success: test_bst_second_largest')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestBstSecondLargest()\n",
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" test.test_bst_second_largest()\n",
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"\n",
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"\n",
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"if __name__ == '__main__':\n",
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" main()"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Solution Notebook\n",
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"\n",
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"Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/check_balance/check_balance_solution.ipynb) for a discussion on algorithms and code solutions."
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 3",
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"language": "python",
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"name": "python3"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.5.0"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 0
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}
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@ -0,0 +1,271 @@
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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Solution Notebook"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Problem: Find the second largest node in a binary search tree.\n",
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"\n",
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"* [Constraints](#Constraints)\n",
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"* [Test Cases](#Test-Cases)\n",
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"* [Algorithm](#Algorithm)\n",
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"* [Code](#Code)\n",
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"* [Unit Test](#Unit-Test)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
|
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"## Constraints\n",
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"\n",
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"* If this is called on a None input or a single node, should we raise an exception?\n",
|
||||
" * Yes\n",
|
||||
" * None -> TypeError\n",
|
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" * Single node -> ValueError\n",
|
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"* Can we assume we already have a Node class with an insert method?\n",
|
||||
" * Yes\n",
|
||||
"* Can we assume this fits memory?\n",
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" * Yes"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Test Cases\n",
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"\n",
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"* None or single node -> Exception\n",
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"\n",
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"<pre>\n",
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"Input:\n",
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" _10_\n",
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" _/ \\_ \n",
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" 5 15\n",
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" / \\ / \\\n",
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" 3 8 12 20\n",
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" / \\ \\\n",
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" 2 4 30\n",
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"\n",
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"Output: 20\n",
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"\n",
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"Input:\n",
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" 10\n",
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" / \n",
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" 5\n",
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" / \\\n",
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" 3 7\n",
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"Output: 7\n",
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"</pre>"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Algorithm\n",
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"\n",
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"<pre>\n",
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"\n",
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"If there is no right node, the second largest is the right most left subtree:\n",
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"\n",
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" 10\n",
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" / \n",
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" 5\n",
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" / \\\n",
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" 3 7\n",
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"\n",
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"If there is a right node and the right node has children, recurse to that right child:\n",
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"\n",
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" _10_\n",
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" _/ \\_ \n",
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" 5 15\n",
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" / \\ / \\\n",
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" 3 8 12 20\n",
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" / \\ \\\n",
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" 2 4 30\n",
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"\n",
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"Eventually we'll get to the following scenario:\n",
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"\n",
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" 20\n",
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" \\\n",
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" 30\n",
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"\n",
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"If the right node has no children, the second largest is the current node.\n",
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"\n",
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"</pre>\n",
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"\n",
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"Complexity:\n",
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"* Time: O(h)\n",
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"* Space: O(h), where h is the height of the tree"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Code"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"%run ../bst/bst.py"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 2,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"class Solution(Bst):\n",
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"\n",
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" def _find_second_largest(self, node):\n",
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" if node.right is not None:\n",
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" if node.right.left is not None or node.right.right is not None:\n",
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" return self._find_second_largest(node.right)\n",
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" else:\n",
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" return node\n",
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" else:\n",
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" return self._find_right_most_node(node.left)\n",
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"\n",
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" def _find_right_most_node(self, node):\n",
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" if node.right is not None:\n",
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" return self._find_right_most_node(node.right)\n",
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" else:\n",
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" return node\n",
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"\n",
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" def find_second_largest(self):\n",
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" if self.root is None:\n",
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" raise TypeError('root cannot be None')\n",
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" if self.root.right is None and self.root.left is None:\n",
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" raise ValueError('root must have at least one child')\n",
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" return self._find_second_largest(self.root)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Unit Test"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 3,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Overwriting test_bst_second_largest.py\n"
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]
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}
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],
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"source": [
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"%%writefile test_bst_second_largest.py\n",
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"from nose.tools import assert_equal, assert_raises\n",
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"\n",
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"\n",
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"class TestBstSecondLargest(object):\n",
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"\n",
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" def test_bst_second_largest(self):\n",
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" bst = Solution(None)\n",
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" assert_raises(TypeError, bst.find_second_largest)\n",
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" root = Node(10)\n",
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" bst = Solution(root)\n",
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" node5 = bst.insert(5)\n",
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" node15 = bst.insert(15)\n",
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" node3 = bst.insert(3)\n",
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" node8 = bst.insert(8)\n",
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" node12 = bst.insert(12)\n",
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" node20 = bst.insert(20)\n",
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" node2 = bst.insert(2)\n",
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" node4 = bst.insert(4)\n",
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" node30 = bst.insert(30)\n",
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" assert_equal(bst.find_second_largest(), node20)\n",
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" root = Node(10)\n",
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" bst = Solution(root)\n",
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" node5 = bst.insert(5)\n",
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" node3 = bst.insert(3)\n",
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" node7 = bst.insert(7)\n",
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" assert_equal(bst.find_second_largest(), node7)\n",
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" print('Success: test_bst_second_largest')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestBstSecondLargest()\n",
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" test.test_bst_second_largest()\n",
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"\n",
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"\n",
|
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"if __name__ == '__main__':\n",
|
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" main()"
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]
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},
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{
|
||||
"cell_type": "code",
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"execution_count": 4,
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"metadata": {
|
||||
"collapsed": false
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||||
},
|
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"outputs": [
|
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{
|
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"name": "stdout",
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"output_type": "stream",
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"text": [
|
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"Success: test_bst_second_largest\n"
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]
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}
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],
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"source": [
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"%run -i test_bst_second_largest.py"
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]
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}
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],
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"metadata": {
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"kernelspec": {
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||||
"display_name": "Python 3",
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"language": "python",
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"name": "python3"
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||||
},
|
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"language_info": {
|
||||
"codemirror_mode": {
|
||||
"name": "ipython",
|
||||
"version": 3
|
||||
},
|
||||
"file_extension": ".py",
|
||||
"mimetype": "text/x-python",
|
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"name": "python",
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"nbconvert_exporter": "python",
|
||||
"pygments_lexer": "ipython3",
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"version": "3.5.0"
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||||
}
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},
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"nbformat": 4,
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"nbformat_minor": 0
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}
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36
graphs_trees/bst_second_largest/test_bst_second_largest.py
Normal file
36
graphs_trees/bst_second_largest/test_bst_second_largest.py
Normal file
|
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@ -0,0 +1,36 @@
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from nose.tools import assert_equal, assert_raises
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class TestBstSecondLargest(object):
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def test_bst_second_largest(self):
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bst = Solution(None)
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assert_raises(TypeError, bst.find_second_largest)
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root = Node(10)
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bst = Solution(root)
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node5 = bst.insert(5)
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node15 = bst.insert(15)
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node3 = bst.insert(3)
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node8 = bst.insert(8)
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node12 = bst.insert(12)
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||||
node20 = bst.insert(20)
|
||||
node2 = bst.insert(2)
|
||||
node4 = bst.insert(4)
|
||||
node30 = bst.insert(30)
|
||||
assert_equal(bst.find_second_largest(), node20)
|
||||
root = Node(10)
|
||||
bst = Solution(root)
|
||||
node5 = bst.insert(5)
|
||||
node3 = bst.insert(3)
|
||||
node7 = bst.insert(7)
|
||||
assert_equal(bst.find_second_largest(), node7)
|
||||
print('Success: test_bst_second_largest')
|
||||
|
||||
|
||||
def main():
|
||||
test = TestBstSecondLargest()
|
||||
test.test_bst_second_largest()
|
||||
|
||||
|
||||
if __name__ == '__main__':
|
||||
main()
|
||||
Loading…
Reference in New Issue
Block a user