mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
synced 2024-03-22 13:11:13 +08:00
Add trie challenge
This commit is contained in:
Donne Martin
parent
4f93526ae5
commit
4216c91afc
0
graphs_trees/trie/__init__.py
Normal file
0
graphs_trees/trie/__init__.py
Normal file
74
graphs_trees/trie/test_trie.py
Normal file
74
graphs_trees/trie/test_trie.py
Normal file
|
|
@ -0,0 +1,74 @@
|
|||
from nose.tools import assert_true
|
||||
from nose.tools import raises
|
||||
|
||||
|
||||
class TestTrie(object):
|
||||
|
||||
def test_trie(self):
|
||||
trie = Trie()
|
||||
|
||||
print('Test: Insert')
|
||||
words = ['a', 'at', 'has', 'hat', 'he',
|
||||
'me', 'men', 'mens', 'met']
|
||||
for word in words:
|
||||
trie.insert(word)
|
||||
for word in trie.list_words():
|
||||
assert_true(trie.find(word) is not None)
|
||||
|
||||
print('Test: Remove me')
|
||||
trie.remove('me')
|
||||
words_removed = ['me']
|
||||
words = ['a', 'at', 'has', 'hat', 'he',
|
||||
'men', 'mens', 'met']
|
||||
for word in words:
|
||||
assert_true(trie.find(word) is not None)
|
||||
for word in words_removed:
|
||||
assert_true(trie.find(word) is None)
|
||||
|
||||
print('Test: Remove mens')
|
||||
trie.remove('mens')
|
||||
words_removed = ['me', 'mens']
|
||||
words = ['a', 'at', 'has', 'hat', 'he',
|
||||
'men', 'met']
|
||||
for word in words:
|
||||
assert_true(trie.find(word) is not None)
|
||||
for word in words_removed:
|
||||
assert_true(trie.find(word) is None)
|
||||
|
||||
print('Test: Remove a')
|
||||
trie.remove('a')
|
||||
words_removed = ['a', 'me', 'mens']
|
||||
words = ['at', 'has', 'hat', 'he',
|
||||
'men', 'met']
|
||||
for word in words:
|
||||
assert_true(trie.find(word) is not None)
|
||||
for word in words_removed:
|
||||
assert_true(trie.find(word) is None)
|
||||
|
||||
print('Test: Remove has')
|
||||
trie.remove('has')
|
||||
words_removed = ['a', 'has', 'me', 'mens']
|
||||
words = ['at', 'hat', 'he',
|
||||
'men', 'met']
|
||||
for word in words:
|
||||
assert_true(trie.find(word) is not None)
|
||||
for word in words_removed:
|
||||
assert_true(trie.find(word) is None)
|
||||
|
||||
print('Success: test_trie')
|
||||
|
||||
@raises(Exception)
|
||||
def test_trie_remove_invalid(self):
|
||||
print('Test: Remove from empty trie')
|
||||
trie = Trie()
|
||||
assert_true(trie.remove('foo') is None)
|
||||
|
||||
|
||||
def main():
|
||||
test = TestTrie()
|
||||
test.test_trie()
|
||||
test.test_trie_remove_invalid()
|
||||
|
||||
|
||||
if __name__ == '__main__':
|
||||
main()
|
||||
76
graphs_trees/trie/trie.py
Normal file
76
graphs_trees/trie/trie.py
Normal file
|
|
@ -0,0 +1,76 @@
|
|||
from collections import OrderedDict
|
||||
|
||||
|
||||
class Node(object):
|
||||
|
||||
def __init__(self, key, parent=None, terminates=False):
|
||||
self.key = key
|
||||
self.terminates = False
|
||||
self.parent = parent
|
||||
self.children = {}
|
||||
|
||||
|
||||
class Trie(object):
|
||||
|
||||
def __init__(self):
|
||||
self.root = Node('')
|
||||
|
||||
def find(self, word):
|
||||
if word is None:
|
||||
raise TypeError('word cannot be None')
|
||||
node = self.root
|
||||
for char in word:
|
||||
if char in node.children:
|
||||
node = node.children[char]
|
||||
else:
|
||||
return None
|
||||
return node if node.terminates else None
|
||||
|
||||
def insert(self, word):
|
||||
if word is None:
|
||||
raise TypeError('word cannot be None')
|
||||
node = self.root
|
||||
parent = None
|
||||
for char in word:
|
||||
if char in node.children:
|
||||
node = node.children[char]
|
||||
else:
|
||||
node.children[char] = Node(char, parent=node)
|
||||
node = node.children[char]
|
||||
node.terminates = True
|
||||
|
||||
def remove(self, word):
|
||||
if word is None:
|
||||
raise TypeError('word cannot be None')
|
||||
node = self.find(word)
|
||||
if node is None:
|
||||
raise KeyError('word does not exist')
|
||||
node.terminates = False
|
||||
parent = node.parent
|
||||
while parent is not None:
|
||||
# As we are propagating the delete up the
|
||||
# parents, if this node has children, stop
|
||||
# here to prevent orphaning its children.
|
||||
# Or
|
||||
# if this node is a terminating node that is
|
||||
# not the terminating node of the input word,
|
||||
# stop to prevent removing the associated word.
|
||||
if node.children or node.terminates:
|
||||
return
|
||||
del parent.children[node.key]
|
||||
node = parent
|
||||
parent = parent.parent
|
||||
|
||||
def list_words(self):
|
||||
result = []
|
||||
curr_word = ''
|
||||
self._list_words(self.root, curr_word, result)
|
||||
return result
|
||||
|
||||
def _list_words(self, node, curr_word, result):
|
||||
if node is None:
|
||||
return
|
||||
for key, child in node.children.items():
|
||||
if child.terminates:
|
||||
result.append(curr_word+key)
|
||||
self._list_words(child, curr_word+key, result)
|
||||
279
graphs_trees/trie/trie_challenge.ipynb
Normal file
279
graphs_trees/trie/trie_challenge.ipynb
Normal file
|
|
@ -0,0 +1,279 @@
|
|||
{
|
||||
"cells": [
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"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)."
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"# Challenge Notebook"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Problem: Implement a trie with find, insert, remove, and list_words methods.\n",
|
||||
"\n",
|
||||
"* [Constraints](#Constraints)\n",
|
||||
"* [Test Cases](#Test-Cases)\n",
|
||||
"* [Algorithm](#Algorithm)\n",
|
||||
"* [Code](#Code)\n",
|
||||
"* [Unit Test](#Unit-Test)\n",
|
||||
"* [Solution Notebook](#Solution-Notebook)"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Constraints\n",
|
||||
"\n",
|
||||
"* Can we assume we are working with strings?\n",
|
||||
" * Yes\n",
|
||||
"* Are the strings in ASCII?\n",
|
||||
" * Yes\n",
|
||||
"* Should `find` only match exact words with a terminating character?\n",
|
||||
" * Yes\n",
|
||||
"* Should `list_words` only return words with a terminating character?\n",
|
||||
" * Yes\n",
|
||||
"* Can we assume this fits memory?\n",
|
||||
" * Yes"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Test Cases\n",
|
||||
"\n",
|
||||
"<pre>\n",
|
||||
"\n",
|
||||
" root\n",
|
||||
" / | \\\n",
|
||||
" h a* m\n",
|
||||
" / \\ \\ \\\n",
|
||||
" a e* t* e*\n",
|
||||
" / \\ / \\\n",
|
||||
" s* t* n* t*\n",
|
||||
" /\n",
|
||||
" s*\n",
|
||||
"\n",
|
||||
"find\n",
|
||||
"\n",
|
||||
"* Find on an empty trie\n",
|
||||
"* Find non-matching\n",
|
||||
"* Find matching\n",
|
||||
"\n",
|
||||
"insert\n",
|
||||
"\n",
|
||||
"* Insert on empty trie\n",
|
||||
"* Insert to make a leaf terminator char\n",
|
||||
"* Insert to extend an existing terminator char\n",
|
||||
"\n",
|
||||
"remove\n",
|
||||
"\n",
|
||||
"* Remove me\n",
|
||||
"* Remove mens\n",
|
||||
"* Remove a\n",
|
||||
"* Remove has\n",
|
||||
"\n",
|
||||
"list_words\n",
|
||||
"\n",
|
||||
"* List empty\n",
|
||||
"* List general case\n",
|
||||
"</pre>\n",
|
||||
"\n"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Algorithm\n",
|
||||
"\n",
|
||||
"Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/trie/trie_solution.ipynb). If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Code"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"from collections import OrderedDict\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class Node(object):\n",
|
||||
"\n",
|
||||
" def __init__(self, data, parent=None, terminates=False):\n",
|
||||
" # TODO: Implement me\n",
|
||||
" pass\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class Trie(object):\n",
|
||||
"\n",
|
||||
" def __init__(self):\n",
|
||||
" # TODO: Implement me\n",
|
||||
" pass\n",
|
||||
"\n",
|
||||
" def find(self, word):\n",
|
||||
" # TODO: Implement me\n",
|
||||
" pass\n",
|
||||
"\n",
|
||||
" def insert(self, word):\n",
|
||||
" # TODO: Implement me\n",
|
||||
" pass\n",
|
||||
"\n",
|
||||
" def remove(self, word):\n",
|
||||
" # TODO: Implement me\n",
|
||||
" pass\n",
|
||||
"\n",
|
||||
" def list_words(self):\n",
|
||||
" # TODO: Implement me\n",
|
||||
" pass"
|
||||
]
|
||||
},
|
||||
{
|
||||
"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": false
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"# %load test_trie.py\n",
|
||||
"from nose.tools import assert_true\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class TestTrie(object):\n",
|
||||
"\n",
|
||||
" def test_trie(self):\n",
|
||||
" print('Test: Remove from empty trie')\n",
|
||||
" trie = Trie()\n",
|
||||
" assert_true(trie.remove('foo') is None)\n",
|
||||
"\n",
|
||||
" print('Test: Insert')\n",
|
||||
" words = ['a', 'at', 'has', 'hat', 'he',\n",
|
||||
" 'me', 'men', 'mens', 'met']\n",
|
||||
" for word in words:\n",
|
||||
" trie.insert(word)\n",
|
||||
" for word in trie.list_words():\n",
|
||||
" assert_true(trie.find(word) is not None)\n",
|
||||
"\n",
|
||||
" # Remove me\n",
|
||||
" # Remove mens\n",
|
||||
" # Remove a\n",
|
||||
" \n",
|
||||
" print('Test: Remove me')\n",
|
||||
" trie.remove('me')\n",
|
||||
" words_removed = ['me']\n",
|
||||
" words = ['a', 'at', 'has', 'hat', 'he',\n",
|
||||
" 'men', 'mens', 'met']\n",
|
||||
" for word in words:\n",
|
||||
" assert_true(trie.find(word) is not None)\n",
|
||||
" for word in words_removed:\n",
|
||||
" assert_true(trie.find(word) is None)\n",
|
||||
"\n",
|
||||
" print('Test: Remove mens')\n",
|
||||
" trie.remove('mens')\n",
|
||||
" words_removed = ['me', 'mens']\n",
|
||||
" words = ['a', 'at', 'has', 'hat', 'he',\n",
|
||||
" 'men', 'met']\n",
|
||||
" for word in words:\n",
|
||||
" assert_true(trie.find(word) is not None)\n",
|
||||
" for word in words_removed:\n",
|
||||
" assert_true(trie.find(word) is None)\n",
|
||||
"\n",
|
||||
" print('Test: Remove a')\n",
|
||||
" trie.remove('a')\n",
|
||||
" words_removed = ['a', 'me', 'mens']\n",
|
||||
" words = ['at', 'has', 'hat', 'he',\n",
|
||||
" 'men', 'met']\n",
|
||||
" for word in words:\n",
|
||||
" assert_true(trie.find(word) is not None)\n",
|
||||
" for word in words_removed:\n",
|
||||
" assert_true(trie.find(word) is None)\n",
|
||||
"\n",
|
||||
" print('Test: Remove has')\n",
|
||||
" trie.remove('has')\n",
|
||||
" words_removed = ['a', 'has', 'me', 'mens']\n",
|
||||
" words = ['at', 'hat', 'he',\n",
|
||||
" 'men', 'met']\n",
|
||||
" for word in words:\n",
|
||||
" assert_true(trie.find(word) is not None)\n",
|
||||
" for word in words_removed:\n",
|
||||
" assert_true(trie.find(word) is None)\n",
|
||||
"\n",
|
||||
" print('Success: test_trie')\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"def main():\n",
|
||||
" test = TestTrie()\n",
|
||||
" test.test_trie()\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"if __name__ == '__main__':\n",
|
||||
" main()"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Solution Notebook\n",
|
||||
"\n",
|
||||
"Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/trie/trie_solution.ipynb) for a discussion on algorithms and code solutions."
|
||||
]
|
||||
}
|
||||
],
|
||||
"metadata": {
|
||||
"kernelspec": {
|
||||
"display_name": "Python 3",
|
||||
"language": "python",
|
||||
"name": "python3"
|
||||
},
|
||||
"language_info": {
|
||||
"codemirror_mode": {
|
||||
"name": "ipython",
|
||||
"version": 3
|
||||
},
|
||||
"file_extension": ".py",
|
||||
"mimetype": "text/x-python",
|
||||
"name": "python",
|
||||
"nbconvert_exporter": "python",
|
||||
"pygments_lexer": "ipython3",
|
||||
"version": "3.5.0"
|
||||
}
|
||||
},
|
||||
"nbformat": 4,
|
||||
"nbformat_minor": 0
|
||||
}
|
||||
418
graphs_trees/trie/trie_solution.ipynb
Normal file
418
graphs_trees/trie/trie_solution.ipynb
Normal file
|
|
@ -0,0 +1,418 @@
|
|||
{
|
||||
"cells": [
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"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)."
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"# Solution Notebook"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Problem: Implement a trie with find, insert, remove, and list_words methods.\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 strings?\n",
|
||||
" * Yes\n",
|
||||
"* Are the strings in ASCII?\n",
|
||||
" * Yes\n",
|
||||
"* Should `find` only match exact words with a terminating character?\n",
|
||||
" * Yes\n",
|
||||
"* Should `list_words` only return words with a terminating character?\n",
|
||||
" * Yes\n",
|
||||
"* Can we assume this fits memory?\n",
|
||||
" * Yes"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Test Cases\n",
|
||||
"\n",
|
||||
"<pre>\n",
|
||||
"\n",
|
||||
"root node is denoted by ''\n",
|
||||
"\n",
|
||||
" ''\n",
|
||||
" / | \\\n",
|
||||
" h a* m\n",
|
||||
" / \\ \\ \\\n",
|
||||
" a e* t* e*\n",
|
||||
" / \\ / \\\n",
|
||||
" s* t* n* t*\n",
|
||||
" /\n",
|
||||
" s*\n",
|
||||
"\n",
|
||||
"find\n",
|
||||
"\n",
|
||||
"* Find on an empty trie\n",
|
||||
"* Find non-matching\n",
|
||||
"* Find matching\n",
|
||||
"\n",
|
||||
"insert\n",
|
||||
"\n",
|
||||
"* Insert on empty trie\n",
|
||||
"* Insert to make a leaf terminator char\n",
|
||||
"* Insert to extend an existing terminator char\n",
|
||||
"\n",
|
||||
"remove\n",
|
||||
"\n",
|
||||
"* Remove me\n",
|
||||
"* Remove mens\n",
|
||||
"* Remove a\n",
|
||||
"* Remove has\n",
|
||||
"\n",
|
||||
"list_words\n",
|
||||
"\n",
|
||||
"* List empty\n",
|
||||
"* List general case\n",
|
||||
"</pre>\n",
|
||||
"\n",
|
||||
"\n"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Algorithm\n",
|
||||
"\n",
|
||||
"### find\n",
|
||||
"\n",
|
||||
"* Set node to the root\n",
|
||||
"* For each char in the input word\n",
|
||||
" * Check the current node's children to see if it contains the char\n",
|
||||
" * If a child has the char, set node to the child\n",
|
||||
" * Else, return None\n",
|
||||
"* Return the last child node if it has a terminator, else None\n",
|
||||
"\n",
|
||||
"Complexity:\n",
|
||||
"* Time: O(m), where m is the length of the word\n",
|
||||
"* Space: O(h) for the recursion depth (tree height), or O(1) if using an iterative approach\n",
|
||||
"\n",
|
||||
"### insert\n",
|
||||
"\n",
|
||||
"* set node to the root\n",
|
||||
"* For each char in the input word\n",
|
||||
" * Check the current node's children to see if it contains the char\n",
|
||||
" * If a child has the char, set node to the child\n",
|
||||
" * Else, insert a new node with the char\n",
|
||||
" * Update children and parents\n",
|
||||
"* Set the last node as a terminating node\n",
|
||||
"\n",
|
||||
"Complexity:\n",
|
||||
"* Time: O(m), where m is the length of the word\n",
|
||||
"* Space: O(h) for the recursion depth (tree height), or O(1) if using an iterative approach\n",
|
||||
"\n",
|
||||
"### remove\n",
|
||||
"\n",
|
||||
"* Determine the matching terminating node by calling the find method\n",
|
||||
"* If the matching node has children, remove the terminator to prevent orphaning its children\n",
|
||||
"* Set the parent node to the matching node's parent\n",
|
||||
"* We'll be looping up the parent chain to propagate the delete\n",
|
||||
"* While the parent is valid\n",
|
||||
" * If the node has children\n",
|
||||
" * Return to prevent orphaning its remaining children\n",
|
||||
" * If the node is a terminating node and it isn't the original matching node from the find call\n",
|
||||
" * Return to prevent deleting this additional valid word\n",
|
||||
" * Remove the parent node's child entry matching the node\n",
|
||||
" * Set the node to the parent\n",
|
||||
" * Set the parent to the parent's parent\n",
|
||||
"\n",
|
||||
"Complexity:\n",
|
||||
"* Time: O(m+h), where where m is the length of the word and h is the tree height\n",
|
||||
"* Space: O(h) for the recursion depth (tree height), or O(1) if using an iterative approach\n",
|
||||
"\n",
|
||||
"### list_words\n",
|
||||
"\n",
|
||||
"* Do a pre-order traversal, passing down the current word\n",
|
||||
" * When you reach a terminating node, add it to the list of results\n",
|
||||
"\n",
|
||||
"Complexity:\n",
|
||||
"* Time: O(n)\n",
|
||||
"* Space: O(h) for the recursion depth (tree height), or O(1) if using an iterative approach"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Code"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 1,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"Overwriting trie.py\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"source": [
|
||||
"%%writefile trie.py\n",
|
||||
"from collections import OrderedDict\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class Node(object):\n",
|
||||
"\n",
|
||||
" def __init__(self, key, parent=None, terminates=False):\n",
|
||||
" self.key = key\n",
|
||||
" self.terminates = False\n",
|
||||
" self.parent = parent\n",
|
||||
" self.children = {}\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class Trie(object):\n",
|
||||
"\n",
|
||||
" def __init__(self):\n",
|
||||
" self.root = Node('')\n",
|
||||
"\n",
|
||||
" def find(self, word):\n",
|
||||
" if word is None:\n",
|
||||
" raise TypeError('word cannot be None')\n",
|
||||
" node = self.root\n",
|
||||
" for char in word:\n",
|
||||
" if char in node.children:\n",
|
||||
" node = node.children[char]\n",
|
||||
" else:\n",
|
||||
" return None\n",
|
||||
" return node if node.terminates else None\n",
|
||||
"\n",
|
||||
" def insert(self, word):\n",
|
||||
" if word is None:\n",
|
||||
" raise TypeError('word cannot be None')\n",
|
||||
" node = self.root\n",
|
||||
" parent = None\n",
|
||||
" for char in word:\n",
|
||||
" if char in node.children:\n",
|
||||
" node = node.children[char]\n",
|
||||
" else:\n",
|
||||
" node.children[char] = Node(char, parent=node)\n",
|
||||
" node = node.children[char]\n",
|
||||
" node.terminates = True\n",
|
||||
"\n",
|
||||
" def remove(self, word):\n",
|
||||
" if word is None:\n",
|
||||
" raise TypeError('word cannot be None')\n",
|
||||
" node = self.find(word)\n",
|
||||
" if node is None:\n",
|
||||
" raise KeyError('word does not exist')\n",
|
||||
" node.terminates = False\n",
|
||||
" parent = node.parent\n",
|
||||
" while parent is not None:\n",
|
||||
" # As we are propagating the delete up the \n",
|
||||
" # parents, if this node has children, stop\n",
|
||||
" # here to prevent orphaning its children.\n",
|
||||
" # Or\n",
|
||||
" # if this node is a terminating node that is\n",
|
||||
" # not the terminating node of the input word, \n",
|
||||
" # stop to prevent removing the associated word.\n",
|
||||
" if node.children or node.terminates:\n",
|
||||
" return\n",
|
||||
" del parent.children[node.key]\n",
|
||||
" node = parent\n",
|
||||
" parent = parent.parent\n",
|
||||
"\n",
|
||||
" def list_words(self):\n",
|
||||
" result = []\n",
|
||||
" curr_word = ''\n",
|
||||
" self._list_words(self.root, curr_word, result)\n",
|
||||
" return result\n",
|
||||
"\n",
|
||||
" def _list_words(self, node, curr_word, result):\n",
|
||||
" if node is None:\n",
|
||||
" return\n",
|
||||
" for key, child in node.children.items():\n",
|
||||
" if child.terminates:\n",
|
||||
" result.append(curr_word + key)\n",
|
||||
" self._list_words(child, curr_word + key, result)"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 2,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"%run trie.py"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Unit Test"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 3,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"Overwriting test_trie.py\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"source": [
|
||||
"%%writefile test_trie.py\n",
|
||||
"from nose.tools import assert_true\n",
|
||||
"from nose.tools import raises\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class TestTrie(object): \n",
|
||||
"\n",
|
||||
" def test_trie(self):\n",
|
||||
" trie = Trie()\n",
|
||||
"\n",
|
||||
" print('Test: Insert')\n",
|
||||
" words = ['a', 'at', 'has', 'hat', 'he',\n",
|
||||
" 'me', 'men', 'mens', 'met']\n",
|
||||
" for word in words:\n",
|
||||
" trie.insert(word)\n",
|
||||
" for word in trie.list_words():\n",
|
||||
" assert_true(trie.find(word) is not None)\n",
|
||||
" \n",
|
||||
" print('Test: Remove me')\n",
|
||||
" trie.remove('me')\n",
|
||||
" words_removed = ['me']\n",
|
||||
" words = ['a', 'at', 'has', 'hat', 'he',\n",
|
||||
" 'men', 'mens', 'met']\n",
|
||||
" for word in words:\n",
|
||||
" assert_true(trie.find(word) is not None)\n",
|
||||
" for word in words_removed:\n",
|
||||
" assert_true(trie.find(word) is None)\n",
|
||||
"\n",
|
||||
" print('Test: Remove mens')\n",
|
||||
" trie.remove('mens')\n",
|
||||
" words_removed = ['me', 'mens']\n",
|
||||
" words = ['a', 'at', 'has', 'hat', 'he',\n",
|
||||
" 'men', 'met']\n",
|
||||
" for word in words:\n",
|
||||
" assert_true(trie.find(word) is not None)\n",
|
||||
" for word in words_removed:\n",
|
||||
" assert_true(trie.find(word) is None)\n",
|
||||
"\n",
|
||||
" print('Test: Remove a')\n",
|
||||
" trie.remove('a')\n",
|
||||
" words_removed = ['a', 'me', 'mens']\n",
|
||||
" words = ['at', 'has', 'hat', 'he',\n",
|
||||
" 'men', 'met']\n",
|
||||
" for word in words:\n",
|
||||
" assert_true(trie.find(word) is not None)\n",
|
||||
" for word in words_removed:\n",
|
||||
" assert_true(trie.find(word) is None)\n",
|
||||
"\n",
|
||||
" print('Test: Remove has')\n",
|
||||
" trie.remove('has')\n",
|
||||
" words_removed = ['a', 'has', 'me', 'mens']\n",
|
||||
" words = ['at', 'hat', 'he',\n",
|
||||
" 'men', 'met']\n",
|
||||
" for word in words:\n",
|
||||
" assert_true(trie.find(word) is not None)\n",
|
||||
" for word in words_removed:\n",
|
||||
" assert_true(trie.find(word) is None)\n",
|
||||
"\n",
|
||||
" print('Success: test_trie')\n",
|
||||
"\n",
|
||||
" @raises(Exception)\n",
|
||||
" def test_trie_remove_invalid(self):\n",
|
||||
" print('Test: Remove from empty trie')\n",
|
||||
" trie = Trie()\n",
|
||||
" assert_true(trie.remove('foo') is None) \n",
|
||||
"\n",
|
||||
"\n",
|
||||
"def main():\n",
|
||||
" test = TestTrie()\n",
|
||||
" test.test_trie()\n",
|
||||
" test.test_trie_remove_invalid()\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"if __name__ == '__main__':\n",
|
||||
" main()"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 4,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"Test: Insert\n",
|
||||
"Test: Remove me\n",
|
||||
"Test: Remove mens\n",
|
||||
"Test: Remove a\n",
|
||||
"Test: Remove has\n",
|
||||
"Success: test_trie\n",
|
||||
"Test: Remove from empty trie\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"source": [
|
||||
"%run -i test_trie.py"
|
||||
]
|
||||
}
|
||||
],
|
||||
"metadata": {
|
||||
"kernelspec": {
|
||||
"display_name": "Python 3",
|
||||
"language": "python",
|
||||
"name": "python3"
|
||||
},
|
||||
"language_info": {
|
||||
"codemirror_mode": {
|
||||
"name": "ipython",
|
||||
"version": 3
|
||||
},
|
||||
"file_extension": ".py",
|
||||
"mimetype": "text/x-python",
|
||||
"name": "python",
|
||||
"nbconvert_exporter": "python",
|
||||
"pygments_lexer": "ipython3",
|
||||
"version": "3.4.3"
|
||||
}
|
||||
},
|
||||
"nbformat": 4,
|
||||
"nbformat_minor": 0
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user