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Added binary search tree challenge.

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Donne Martin
2015-08-01 09:25:14 -04:00
parent 757eca26f1
commit a6c7f71379
5 changed files with 539 additions and 0 deletions
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0
graphs_trees/bst/__init__.py Normal file
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53
graphs_trees/bst/bst.py Normal file
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from collections import deque
class Node(object):
def __init__(self, data):
self.data = data
self.left = None
self.right = None
def insert(self, data):
if data <= self.data:
if self.left is None:
self.left = Node(data)
else:
self.left.insert(data)
else:
if self.right is None:
self.right = Node(data)
else:
self.right.insert(data)
def in_order_traversal(self, visit_func):
if self.left is not None:
self.left.in_order_traversal(visit_func)
visit_func(self.data)
if self.right is not None:
self.right.in_order_traversal(visit_func)
def pre_order_traversal(self, visit_func):
visit_func(self.data)
if self.left is not None:
self.left.pre_order_traversal(visit_func)
if self.right is not None:
self.right.pre_order_traversal(visit_func)
def post_order_traversal(self, visit_func):
if self.left is not None:
self.left.post_order_traversal(visit_func)
if self.right is not None:
self.right.post_order_traversal(visit_func)
visit_func(self.data)
def bfs(self, visit_func):
queue = deque()
queue.append(self)
while len(queue) > 0:
node = queue.popleft()
visit_func(node.data)
if node.left is not None:
queue.append(node.left)
if node.right is not None:
queue.append(node.right)

211
graphs_trees/bst/bst_challenge.ipynb Normal file
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{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<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>"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Challenge Notebook"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Problem: Implement a binary search tree with an insert method.\n",
"\n",
"* [Constraints](#Constraints)\n",
"* [Test Cases](#Test-Cases)\n",
"* [Algorithm](#Algorithm)\n",
"* [Code](#Code)\n",
"* [Unit Test](#Unit-Test)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Constraints\n",
"\n",
"* Can we assume we are working with valid integers?\n",
" * Yes\n",
"* Can we assume all left descendents <= n < all right descendents?\n",
" * Yes\n",
"* For simplicity, can we use just a Node class without a wrapper Tree class?\n",
" * Yes"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Test Cases\n",
"\n",
"### Insert\n",
"\n",
"Insert will be tested through the following traversal:\n",
"\n",
"### In-Order Traversal (Provided)\n",
"\n",
"* 5, 2, 8, 1, 3 -> 1, 2, 3, 5, 8\n",
"* 1, 2, 3, 4, 5 -> 1, 2, 3, 4, 5"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Algorithm\n",
"\n",
"Refer to the [solution notebook](https://github.com/donnemartin/interactive-coding-challenges/graphs_trees/bst/bst_solution.ipynb). If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Code"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Note: `in_order_traversal` is provided for testing purposes."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"class Node(object):\n",
"\n",
" def __init__(self, data):\n",
" # TODO: Implement me\n",
"\n",
" def insert(self, data):\n",
" # TODO: Implement me\n",
"\n",
" def in_order_traversal(self, visit_func):\n",
" if self.left is not None:\n",
" self.left.in_order_traversal(visit_func)\n",
" visit_func(self.data)\n",
" if self.right is not None:\n",
" self.right.in_order_traversal(visit_func)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Unit Test"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"**The following unit test is expected to fail until you solve the challenge.**"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"%run ../utils/captured_output.py"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"# %load test_bst.py\n",
"from __future__ import print_function\n",
"from nose.tools import assert_equal\n",
"\n",
"\n",
"class TestTree(object):\n",
"\n",
" def test_tree(self):\n",
" root = Node(5)\n",
" root.insert(2)\n",
" root.insert(8)\n",
" root.insert(1)\n",
" root.insert(3)\n",
"\n",
" with captured_output() as (out, err):\n",
" root.in_order_traversal(sys.stdout.write)\n",
" assert_equal(out.getvalue().strip(), '12358')\n",
"\n",
" root = Node(1)\n",
" root.insert(2)\n",
" root.insert(3)\n",
" root.insert(4)\n",
" root.insert(5)\n",
"\n",
" with captured_output() as (out, err):\n",
" root.in_order_traversal(sys.stdout.write)\n",
" assert_equal(out.getvalue().strip(), '12345')\n",
"\n",
" print('Success: test_tree')\n",
"\n",
"\n",
"def main():\n",
" test = TestTree()\n",
" test.test_tree()\n",
"\n",
"\n",
"if __name__ == '__main__':\n",
" main()"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Solution Notebook\n",
"\n",
"Review the [solution notebook](https://github.com/donnemartin/interactive-coding-challenges/graphs_trees/bst/bst_solution.ipynb) for a discussion on algorithms and code solutions."
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 2",
"language": "python",
"name": "python2"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 2
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython2",
"version": "2.7.10"
}
},
"nbformat": 4,
"nbformat_minor": 0
}

238
graphs_trees/bst/bst_solution.ipynb Normal file
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{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<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>"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Solution Notebook"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Problem: Implement a binary search tree with an insert method.\n",
"\n",
"* [Constraints](#Constraints)\n",
"* [Test Cases](#Test-Cases)\n",
"* [Algorithm](#Algorithm)\n",
"* [Code](#Code)\n",
"* [Unit Test](#Unit-Test)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Constraints\n",
"\n",
"* Can we assume we are working with valid integers?\n",
" * Yes\n",
"* Can we assume all left descendents <= n < all right descendents?\n",
" * Yes\n",
"* For simplicity, can we use just a Node class without a wrapper Tree class?\n",
" * Yes"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Test Cases\n",
"\n",
"### Insert\n",
"\n",
"Insert will be tested through the following traversal:\n",
"\n",
"### In-Order Traversal (Provided)\n",
"\n",
"* 5, 2, 8, 1, 3 -> 1, 2, 3, 5, 8\n",
"* 1, 2, 3, 4, 5 -> 1, 2, 3, 4, 5"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Algorithm\n",
"\n",
"### Insert\n",
"\n",
"* If the data is <= the current node's data\n",
" * If the current node's left child is None, set it to Node(data)\n",
" * Else, recursively call insert on the left child\n",
"* Else\n",
" * If the current node's right child is None, set it to Node(data)\n",
" * Else, recursively call insert on the right child\n",
"\n",
"Complexity:\n",
"\n",
"* Time: O(log n)\n",
"* Space: O(1)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Code"
]
},
{
"cell_type": "code",
"execution_count": 1,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"class Node(object):\n",
"\n",
" def __init__(self, data):\n",
" self.data = data\n",
" self.left = None\n",
" self.right = None\n",
"\n",
" def insert(self, data):\n",
" if data <= self.data:\n",
" if self.left is None:\n",
" self.left = Node(data)\n",
" else:\n",
" self.left.insert(data)\n",
" else:\n",
" if self.right is None:\n",
" self.right = Node(data)\n",
" else:\n",
" self.right.insert(data)\n",
"\n",
" def in_order_traversal(self, visit_func):\n",
" if self.left is not None:\n",
" self.left.in_order_traversal(visit_func)\n",
" visit_func(self.data)\n",
" if self.right is not None:\n",
" self.right.in_order_traversal(visit_func)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Unit Test"
]
},
{
"cell_type": "code",
"execution_count": 2,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"%run ../utils/captured_output.py"
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Overwriting test_bst.py\n"
]
}
],
"source": [
"%%writefile test_bst.py\n",
"from __future__ import print_function\n",
"from nose.tools import assert_equal\n",
"\n",
"\n",
"class TestTree(object):\n",
"\n",
" def test_tree(self):\n",
" root = Node(5)\n",
" root.insert(2)\n",
" root.insert(8)\n",
" root.insert(1)\n",
" root.insert(3)\n",
"\n",
" with captured_output() as (out, err):\n",
" root.in_order_traversal(sys.stdout.write)\n",
" assert_equal(out.getvalue().strip(), '12358')\n",
"\n",
" root = Node(1)\n",
" root.insert(2)\n",
" root.insert(3)\n",
" root.insert(4)\n",
" root.insert(5)\n",
"\n",
" with captured_output() as (out, err):\n",
" root.in_order_traversal(sys.stdout.write)\n",
" assert_equal(out.getvalue().strip(), '12345')\n",
"\n",
" print('Success: test_tree')\n",
"\n",
"\n",
"def main():\n",
" test = TestTree()\n",
" test.test_tree()\n",
"\n",
"\n",
"if __name__ == '__main__':\n",
" main()"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Success: test_tree\n"
]
}
],
"source": [
"%run -i test_bst.py"
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 2",
"language": "python",
"name": "python2"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 2
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython2",
"version": "2.7.10"
}
},
"nbformat": 4,
"nbformat_minor": 0
}

37
graphs_trees/bst/test_bst.py Normal file
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from __future__ import print_function
from nose.tools import assert_equal
class TestTree(object):
def test_tree(self):
root = Node(5)
root.insert(2)
root.insert(8)
root.insert(1)
root.insert(3)
with captured_output() as (out, err):
root.in_order_traversal(sys.stdout.write)
assert_equal(out.getvalue().strip(), '12358')
root = Node(1)
root.insert(2)
root.insert(3)
root.insert(4)
root.insert(5)
with captured_output() as (out, err):
root.in_order_traversal(sys.stdout.write)
assert_equal(out.getvalue().strip(), '12345')
print('Success: test_tree')
def main():
test = TestTree()
test.test_tree()
if __name__ == '__main__':
main()