mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
synced 2024-03-22 13:11:13 +08:00
Add invert tree challenge
This commit is contained in:
Donne Martin
parent
98b7887245
commit
2a368b42b6
0
graphs_trees/invert_tree/__init__.py
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0
graphs_trees/invert_tree/__init__.py
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200
graphs_trees/invert_tree/invert_tree_challenge.ipynb
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200
graphs_trees/invert_tree/invert_tree_challenge.ipynb
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@ -0,0 +1,200 @@
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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: Invert a binary 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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"* What does it mean to invert a binary tree?\n",
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" * Swap all left and right node pairs\n",
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"* Can we assume we already have a Node class?\n",
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" * Yes\n",
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"* Can we assume the inputs are valid?\n",
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" * No\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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"<pre>\n",
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"Input:\n",
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" 5\n",
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" / \\\n",
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" 2 7\n",
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" / \\ / \\\n",
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"1 3 6 9\n",
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"\n",
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"Output:\n",
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" 5\n",
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" / \\\n",
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" 7 2\n",
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" / \\ / \\\n",
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"9 6 3 1\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](). 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"
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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 InverseBst(Bst):\n",
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"\n",
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" def invert_tree(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_invert_tree.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 TestInvertTree(object):\n",
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"\n",
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" def test_invert_tree(self):\n",
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" root = Node(5)\n",
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" bst = InverseBst(root)\n",
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" node2 = bst.insert(2)\n",
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" node3 = bst.insert(3)\n",
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" node1 = bst.insert(1)\n",
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" node7 = bst.insert(7)\n",
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" node6 = bst.insert(6)\n",
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" node9 = bst.insert(9)\n",
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" result = bst.invert_tree()\n",
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" assert_equal(result, root)\n",
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" assert_equal(result.left, node7)\n",
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" assert_equal(result.right, node2)\n",
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" assert_equal(result.left.left, node9)\n",
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" assert_equal(result.left.right, node6)\n",
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" assert_equal(result.right.left, node3)\n",
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" assert_equal(result.right.right, node1)\n",
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" print('Success: test_invert_tree')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestInvertTree()\n",
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" test.test_invert_tree()\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]() 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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229
graphs_trees/invert_tree/invert_tree_solution.ipynb
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graphs_trees/invert_tree/invert_tree_solution.ipynb
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@ -0,0 +1,229 @@
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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: Invert a binary 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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"* What does it mean to invert a binary tree?\n",
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" * Swap all left and right node pairs\n",
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"* Can we assume we already have a Node class?\n",
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" * Yes\n",
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"* Can we assume the inputs are valid?\n",
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" * No\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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"<pre>\n",
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"Input:\n",
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" 5\n",
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" / \\\n",
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" 2 7\n",
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" / \\ / \\\n",
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"1 3 6 9\n",
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"\n",
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"Output:\n",
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" 5\n",
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" / \\\n",
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" 7 2\n",
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" / \\ / \\\n",
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"9 6 3 1\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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"* Base case\n",
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" * If the root is None, return\n",
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"* Recursive case\n",
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" * Recurse on the left node\n",
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" * Recurse on the right node\n",
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" * Swap left and right\n",
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"* Return the node\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, for the recursion depth"
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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": false
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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 InverseBst(Bst):\n",
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"\n",
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" def invert_tree(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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" return self._invert_tree(self.root)\n",
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"\n",
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" def _invert_tree(self, root):\n",
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" if root is None:\n",
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" return\n",
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" self._invert_tree(root.left)\n",
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" self._invert_tree(root.right)\n",
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" root.left, root.right = root.right, root.left\n",
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" return 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_invert_tree.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_invert_tree.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 TestInvertTree(object):\n",
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"\n",
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" def test_invert_tree(self):\n",
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" root = Node(5)\n",
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" bst = InverseBst(root)\n",
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" node2 = bst.insert(2)\n",
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" node3 = bst.insert(3)\n",
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" node1 = bst.insert(1)\n",
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" node7 = bst.insert(7)\n",
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" node6 = bst.insert(6)\n",
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" node9 = bst.insert(9)\n",
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" result = bst.invert_tree()\n",
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" assert_equal(result, root)\n",
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" assert_equal(result.left, node7)\n",
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" assert_equal(result.right, node2)\n",
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" assert_equal(result.left.left, node9)\n",
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" assert_equal(result.left.right, node6)\n",
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" assert_equal(result.right.left, node3)\n",
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" assert_equal(result.right.right, node1)\n",
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" print('Success: test_invert_tree')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestInvertTree()\n",
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" test.test_invert_tree()\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_invert_tree\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_invert_tree.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": {
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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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32
graphs_trees/invert_tree/test_invert_tree.py
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32
graphs_trees/invert_tree/test_invert_tree.py
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@ -0,0 +1,32 @@
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from nose.tools import assert_equal, assert_raises
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class TestInvertTree(object):
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def test_invert_tree(self):
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root = Node(5)
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bst = InverseBst(root)
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node2 = bst.insert(2)
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node3 = bst.insert(3)
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node1 = bst.insert(1)
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node7 = bst.insert(7)
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node6 = bst.insert(6)
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node9 = bst.insert(9)
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result = bst.invert_tree()
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assert_equal(result, root)
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assert_equal(result.left, node7)
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assert_equal(result.right, node2)
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assert_equal(result.left.left, node9)
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assert_equal(result.left.right, node6)
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assert_equal(result.right.left, node3)
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assert_equal(result.right.right, node1)
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print('Success: test_invert_tree')
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def main():
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test = TestInvertTree()
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test.test_invert_tree()
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if __name__ == '__main__':
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main()
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