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https://github.com/donnemartin/interactive-coding-challenges.git
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Added bst validate challenge.
This commit is contained in:
Donne Martin
parent
c595ea0fd7
commit
f26f61e949
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@ -208,6 +208,7 @@ Challenges, solutions, and unit tests are presented in the form of **IPython/Jup
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| Create a binary search tree with minimal height from a sorted array | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst_min/bst_min_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst_min/bst_min_solution.ipynb) |
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| Create a linked list for each level of a binary tree | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_level_lists/tree_level_lists_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_level_lists/tree_level_lists_solution.ipynb) |
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| Check if a binary tree is balanced | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/check_balance/check_balance_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/check_balance/check_balance_solution.ipynb) |
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| Determine if a tree is a valid binary search tree | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst_validate/bst_validate_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst_validate/bst_validate_solution.ipynb) |
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| Implement a binary search tree | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst/bst_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst/bst_solution.ipynb) |
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| Implement depth-first search on a graph | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_dfs/dfs_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_dfs/dfs_solution.ipynb) |
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| Implement breadth-first search on a graph | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_bfs/bfs_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_bfs/bfs_solution.ipynb) |
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0
graphs_trees/bst_validate/__init__.py
Normal file
0
graphs_trees/bst_validate/__init__.py
Normal file
195
graphs_trees/bst_validate/bst_validate_challenge.ipynb
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195
graphs_trees/bst_validate/bst_validate_challenge.ipynb
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@ -0,0 +1,195 @@
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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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"<small><i>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).</i></small>"
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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: Determine if a tree is a valid 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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"* Can the tree have duplicates?\n",
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" * Yes\n",
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"* Can we assume we already have a Node class?\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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"<pre>\n",
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"Valid:\n",
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" 5\n",
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" / \\\n",
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" 5 8\n",
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" / \\ /\n",
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" 4 6 7\n",
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"\n",
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"Invalid:\n",
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" 5\n",
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" / \\\n",
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" 5 8\n",
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" / \\ /\n",
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" 4 9 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/bst_validate/bst_validate_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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"def validate_bst(node):\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_validate.py\n",
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"from nose.tools import assert_equal\n",
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"\n",
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"\n",
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"class TestBstValidate(object):\n",
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"\n",
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" def test_bst_validate(self):\n",
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" node = Node(5)\n",
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" insert(node, 8)\n",
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" insert(node, 5)\n",
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" insert(node, 6)\n",
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" insert(node, 4)\n",
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" insert(node, 7)\n",
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" assert_equal(validate_bst(node), True)\n",
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"\n",
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" root = Node(5)\n",
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" left = Node(5)\n",
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" right = Node(8)\n",
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" invalid = Node(20)\n",
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" root.left = left\n",
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" root.right = right\n",
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" root.left.right = invalid\n",
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" assert_equal(validate_bst(root), False)\n",
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" print('Success: test_bst_validate')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestBstValidate()\n",
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" test.test_bst_validate()\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/bst_validate/bst_validate_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 2",
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"language": "python",
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"name": "python2"
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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": 2
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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": "ipython2",
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"version": "2.7.10"
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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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228
graphs_trees/bst_validate/bst_validate_solution.ipynb
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228
graphs_trees/bst_validate/bst_validate_solution.ipynb
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@ -0,0 +1,228 @@
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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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"<small><i>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).</i></small>"
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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: Determine if a tree is a valid 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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"* Can the tree have duplicates?\n",
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" * Yes\n",
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"* Can we assume we already have a Node class?\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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"<pre>\n",
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"Valid:\n",
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" 5\n",
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" / \\\n",
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" 5 8\n",
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" / \\ /\n",
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" 4 6 7\n",
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"\n",
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"Invalid:\n",
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" 5\n",
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" / \\\n",
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" 5 8\n",
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" \\ \n",
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" 20\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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"We'll use a recursive solution that valides left <= current < right, passing down the min and max values as we do a depth-first traversal.\n",
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"\n",
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"* If the node is None, return False\n",
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"* If min is set and the node's value <= min, return False\n",
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"* if max is set and the node's value > max, return False\n",
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"* Recursively call the validate function on node.left, updating max\n",
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"* Recursively call the validate function on node.right, updating min\n",
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" \n",
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"Complexity:\n",
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"* Time: O(n)\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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"def validate_bst(node):\n",
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" return __validate_bst__(node, None, None)\n",
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"\n",
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"\n",
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"def __validate_bst__(node, mininum, maximum):\n",
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" if node is None:\n",
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" return True\n",
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" if mininum is not None and node.data <= mininum:\n",
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" return False\n",
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" if maximum is not None and node.data > maximum:\n",
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" return False\n",
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" if not __validate_bst__(node.left, mininum, node.data):\n",
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" return False\n",
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" if not __validate_bst__(node.right, node.data, maximum):\n",
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" return False\n",
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" return True"
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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_validate.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_validate.py\n",
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"from nose.tools import assert_equal\n",
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"\n",
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"\n",
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"class TestBstValidate(object):\n",
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"\n",
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" def test_bst_validate(self):\n",
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" node = Node(5)\n",
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" insert(node, 8)\n",
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" insert(node, 5)\n",
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" insert(node, 6)\n",
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" insert(node, 4)\n",
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" insert(node, 7)\n",
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" assert_equal(validate_bst(node), True)\n",
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"\n",
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" root = Node(5)\n",
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" left = Node(5)\n",
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" right = Node(8)\n",
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" invalid = Node(20)\n",
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" root.left = left\n",
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" root.right = right\n",
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" root.left.right = invalid\n",
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" assert_equal(validate_bst(root), False)\n",
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"\n",
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" print('Success: test_bst_validate')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestBstValidate()\n",
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" test.test_bst_validate()\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": "code",
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"execution_count": 4,
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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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"Success: test_bst_validate\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_validate.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 2",
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"language": "python",
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"name": "python2"
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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": 2
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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": "ipython2",
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"version": "2.7.10"
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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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33
graphs_trees/bst_validate/test_bst_validate.py
Normal file
33
graphs_trees/bst_validate/test_bst_validate.py
Normal file
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@ -0,0 +1,33 @@
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from nose.tools import assert_equal
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class TestBstValidate(object):
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def test_bst_validate(self):
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node = Node(5)
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insert(node, 8)
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insert(node, 5)
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insert(node, 6)
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insert(node, 4)
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insert(node, 7)
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assert_equal(validate_bst(node), True)
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root = Node(5)
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left = Node(5)
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right = Node(8)
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invalid = Node(20)
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root.left = left
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root.right = right
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root.left.right = invalid
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assert_equal(validate_bst(root), False)
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print('Success: test_bst_validate')
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def main():
|
||||
test = TestBstValidate()
|
||||
test.test_bst_validate()
|
||||
|
||||
|
||||
if __name__ == '__main__':
|
||||
main()
|
||||
Loading…
Reference in New Issue
Block a user