mirror of
https://github.com/donnemartin/interactive-coding-challenges
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Add busiest period challenge
This commit is contained in:
Donne Martin
0
online_judges/busiest_period/__init__.py
Normal file
0
online_judges/busiest_period/__init__.py
Normal file
236
online_judges/busiest_period/busiest_period_challenge.ipynb
Normal file
236
online_judges/busiest_period/busiest_period_challenge.ipynb
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@@ -0,0 +1,236 @@
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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": [
|
||||
"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: Given an array of (unix_timestamp, num_people, EventType.ENTER or EventType.EXIT), find the busiest period.\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 we assume the input array is valid?\n",
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" * Check for None\n",
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"* Can we assume the elements of the input array are valid?\n",
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" * Yes\n",
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"* Is the input sorted by time?\n",
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" * No\n",
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"* Can you have enter and exit elements for the same timestamp?\n",
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" * Yes you can, order of enter and exit is not guaranteed\n",
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"* Could we have multiple enter events (or multiple exit events) for the same timestamp?\n",
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" * No\n",
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"* What is the format of the output?\n",
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" * An array of timestamps [t1, t2]\n",
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"* Can we assume the starting number of people is zero?\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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"* None -> TypeError\n",
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"* [] -> None\n",
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"* General case\n",
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"\n",
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"<pre>\n",
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"timestamp num_people event_type\n",
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"1 2 EventType.ENTER\n",
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"3 1 EventType.ENTER\n",
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"3 2 EventType.EXIT\n",
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"7 3 EventType.ENTER\n",
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"8 2 EventType.EXIT\n",
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"9 2 EventType.EXIT\n",
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"\n",
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"result = Period(7, 8)\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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"from enum import Enum\n",
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"\n",
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"\n",
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"class Data(object):\n",
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"\n",
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" def __init__(self, timestamp, num_people, event_type):\n",
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" self.timestamp = timestamp\n",
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" self.num_people = num_people\n",
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" self.event_type = event_type\n",
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"\n",
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" def __lt__(self, other):\n",
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" return self.timestamp < other.timestamp\n",
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"\n",
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"\n",
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"class Period(object):\n",
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"\n",
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" def __init__(self, start, end):\n",
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" self.start = start\n",
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" self.end = end\n",
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"\n",
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" def __eq__(self, other):\n",
|
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" return self.start == other.start and self.end == other.end\n",
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"\n",
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" def __repr__(self):\n",
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" return str(self.start) + ', ' + str(self.end)\n",
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"\n",
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"\n",
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"class EventType(Enum):\n",
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"\n",
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" ENTER = 0\n",
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" EXIT = 1"
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]
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},
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{
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"cell_type": "code",
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||||
"execution_count": null,
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"metadata": {
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||||
"collapsed": false
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},
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"outputs": [],
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"source": [
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"class Solution(object):\n",
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"\n",
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" def find_busiest_period(self, data):\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_find_busiest_period.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 TestSolution(object):\n",
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"\n",
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" def test_find_busiest_period(self):\n",
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" solution = Solution()\n",
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" assert_raises(TypeError, solution.find_busiest_period, None)\n",
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" assert_equal(solution.find_busiest_period([]), None)\n",
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" data = [\n",
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" Data(3, 2, EventType.EXIT),\n",
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" Data(1, 2, EventType.ENTER),\n",
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" Data(3, 1, EventType.ENTER),\n",
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" Data(7, 3, EventType.ENTER),\n",
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" Data(9, 2, EventType.EXIT),\n",
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" Data(8, 2, EventType.EXIT),\n",
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" ]\n",
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" assert_equal(solution.find_busiest_period(data), Period(7, 8))\n",
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" print('Success: test_find_busiest_period')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestSolution()\n",
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" test.test_find_busiest_period()\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": [
|
||||
"## 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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294
online_judges/busiest_period/busiest_period_solution.ipynb
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294
online_judges/busiest_period/busiest_period_solution.ipynb
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@@ -0,0 +1,294 @@
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||||
{
|
||||
"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: Given an array of (unix_timestamp, num_people, EventType.ENTER or EventType.EXIT), find the busiest period.\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 the input array is valid?\n",
|
||||
" * Check for None\n",
|
||||
"* Can we assume the elements of the input array are valid?\n",
|
||||
" * Yes\n",
|
||||
"* Is the input sorted by time?\n",
|
||||
" * No\n",
|
||||
"* Can you have enter and exit elements for the same timestamp?\n",
|
||||
" * Yes you can, order of enter and exit is not guaranteed\n",
|
||||
"* Could we have multiple enter events (or multiple exit events) for the same timestamp?\n",
|
||||
" * No\n",
|
||||
"* What is the format of the output?\n",
|
||||
" * An array of timestamps [t1, t2]\n",
|
||||
"* Can we assume the starting number of people is zero?\n",
|
||||
" * Yes\n",
|
||||
"* Can we assume the inputs are valid?\n",
|
||||
" * No\n",
|
||||
"* Can we assume this fits memory?\n",
|
||||
" * Yes"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Test Cases\n",
|
||||
"\n",
|
||||
"* None -> TypeError\n",
|
||||
"* [] -> None\n",
|
||||
"* General case\n",
|
||||
"\n",
|
||||
"<pre>\n",
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"timestamp num_people event_type\n",
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"3 2 EventType.EXIT\n",
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"1 2 EventType.ENTER\n",
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"3 1 EventType.ENTER\n",
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"7 3 EventType.ENTER\n",
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"9 2 EventType.EXIT\n",
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"8 2 EventType.EXIT\n",
|
||||
"\n",
|
||||
"result = Period(7, 8)\n",
|
||||
"</pre>"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
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||||
"## Algorithm\n",
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||||
"\n",
|
||||
"Since the input is not sorted, we'll need to sort it first by timestamp, ascending.\n",
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"\n",
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"For each interval in the data set:\n",
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"\n",
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"* If this is an \"enter\" event, increment `curr_people`, else, decrement\n",
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"* Since we can have an \"enter\" and \"exit\" event for the same timestamp, we'll need to look ahead one\n",
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" * If the next element has the same timestamp, hold off (continue) on updating `max_people` and `max_period`\n",
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" * Watch out for indexing out-of-bounds at the end of the array\n",
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"* Update `max_people` and `max_period`\n",
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"\n",
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"Sorted:\n",
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"\n",
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"<pre>\n",
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"timestamp num_people event_type curr_people max_people max_period\n",
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"1 2 EventType.ENTER 2 2 [1, 3]\n",
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"3 1 EventType.ENTER 3 2 (not updated) [1, 3]\n",
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"3 2 EventType.EXIT 1 2 [3, 7]\n",
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"7 3 EventType.ENTER 4 4 [7, 8]\n",
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"8 2 EventType.EXIT 2 4 [7, 8]\n",
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"9 2 EventType.EXIT 0 4 [7, 8]\n",
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"</pre>\n",
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"\n",
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"Complexity:\n",
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"* Time: O(nlog(n)) for the sort\n",
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"* Space: O(1), assuming the sort is in-place"
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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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||||
"cell_type": "code",
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"execution_count": 1,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [],
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"source": [
|
||||
"from enum import Enum\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class Data(object):\n",
|
||||
"\n",
|
||||
" def __init__(self, timestamp, num_people, event_type):\n",
|
||||
" self.timestamp = timestamp\n",
|
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" self.num_people = num_people\n",
|
||||
" self.event_type = event_type\n",
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"\n",
|
||||
" def __lt__(self, other):\n",
|
||||
" return self.timestamp < other.timestamp\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class Period(object):\n",
|
||||
"\n",
|
||||
" def __init__(self, start, end):\n",
|
||||
" self.start = start\n",
|
||||
" self.end = end\n",
|
||||
"\n",
|
||||
" def __eq__(self, other):\n",
|
||||
" return self.start == other.start and self.end == other.end\n",
|
||||
"\n",
|
||||
" def __repr__(self):\n",
|
||||
" return str(self.start) + ', ' + str(self.end)\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class EventType(Enum):\n",
|
||||
"\n",
|
||||
" ENTER = 0\n",
|
||||
" EXIT = 1"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 2,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"class Solution(object):\n",
|
||||
"\n",
|
||||
" def find_busiest_period(self, data):\n",
|
||||
" if data is None:\n",
|
||||
" raise TypeError('data cannot be None')\n",
|
||||
" if not data:\n",
|
||||
" return None\n",
|
||||
" data.sort()\n",
|
||||
" max_period = Period(0, 0)\n",
|
||||
" max_people = 0\n",
|
||||
" curr_people = 0\n",
|
||||
" for index, interval in enumerate(data):\n",
|
||||
" if interval.event_type == EventType.ENTER:\n",
|
||||
" curr_people += interval.num_people\n",
|
||||
" elif interval.event_type == EventType.EXIT:\n",
|
||||
" curr_people -= interval.num_people\n",
|
||||
" else:\n",
|
||||
" raise ValueError('Invalid event type')\n",
|
||||
" if (index < len(data) - 1 and \n",
|
||||
" data[index].timestamp == data[index + 1].timestamp):\n",
|
||||
" continue\n",
|
||||
" if curr_people > max_people:\n",
|
||||
" max_people = curr_people\n",
|
||||
" max_period.start = data[index].timestamp\n",
|
||||
" if index < len(data) - 1:\n",
|
||||
" max_period.end = data[index + 1].timestamp\n",
|
||||
" else:\n",
|
||||
" max_period.end = data[index].timestamp\n",
|
||||
" return max_period"
|
||||
]
|
||||
},
|
||||
{
|
||||
"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_find_busiest_period.py\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"source": [
|
||||
"%%writefile test_find_busiest_period.py\n",
|
||||
"from nose.tools import assert_equal, assert_raises\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class TestSolution(object):\n",
|
||||
"\n",
|
||||
" def test_find_busiest_period(self):\n",
|
||||
" solution = Solution()\n",
|
||||
" assert_raises(TypeError, solution.find_busiest_period, None)\n",
|
||||
" assert_equal(solution.find_busiest_period([]), None)\n",
|
||||
" data = [\n",
|
||||
" Data(3, 2, EventType.EXIT),\n",
|
||||
" Data(1, 2, EventType.ENTER),\n",
|
||||
" Data(3, 1, EventType.ENTER),\n",
|
||||
" Data(7, 3, EventType.ENTER),\n",
|
||||
" Data(9, 2, EventType.EXIT),\n",
|
||||
" Data(8, 2, EventType.EXIT),\n",
|
||||
" ]\n",
|
||||
" assert_equal(solution.find_busiest_period(data), Period(7, 8))\n",
|
||||
" print('Success: test_find_busiest_period')\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"def main():\n",
|
||||
" test = TestSolution()\n",
|
||||
" test.test_find_busiest_period()\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_find_busiest_period\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"source": [
|
||||
"%run -i test_find_busiest_period.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": "3.5.0"
|
||||
}
|
||||
},
|
||||
"nbformat": 4,
|
||||
"nbformat_minor": 0
|
||||
}
|
||||
28
online_judges/busiest_period/test_find_busiest_period.py
Normal file
28
online_judges/busiest_period/test_find_busiest_period.py
Normal file
@@ -0,0 +1,28 @@
|
||||
from nose.tools import assert_equal, assert_raises
|
||||
|
||||
|
||||
class TestSolution(object):
|
||||
|
||||
def test_find_busiest_period(self):
|
||||
solution = Solution()
|
||||
assert_raises(TypeError, solution.find_busiest_period, None)
|
||||
assert_equal(solution.find_busiest_period([]), None)
|
||||
data = [
|
||||
Data(3, 2, EventType.EXIT),
|
||||
Data(1, 2, EventType.ENTER),
|
||||
Data(3, 1, EventType.ENTER),
|
||||
Data(7, 3, EventType.ENTER),
|
||||
Data(9, 2, EventType.EXIT),
|
||||
Data(8, 2, EventType.EXIT),
|
||||
]
|
||||
assert_equal(solution.find_busiest_period(data), Period(7, 8))
|
||||
print('Success: test_find_busiest_period')
|
||||
|
||||
|
||||
def main():
|
||||
test = TestSolution()
|
||||
test.test_find_busiest_period()
|
||||
|
||||
|
||||
if __name__ == '__main__':
|
||||
main()
|
||||
Reference in New Issue
Block a user