This notebook was prepared by Donne Martin. Source and license info is on GitHub.

# Challenge Notebook¶

## Constraints¶

• Can we assume the input array is valid?
• Check for None
• Can we assume the elements of the input array are valid?
• Yes
• Is the input sorted by time?
• No
• Can you have enter and exit elements for the same timestamp?
• Yes you can, order of enter and exit is not guaranteed
• Could we have multiple enter events (or multiple exit events) for the same timestamp?
• No
• What is the format of the output?
• An array of timestamps [t1, t2]
• Can we assume the starting number of people is zero?
• Yes
• Can we assume the inputs are valid?
• No
• Can we assume this fits memory?
• Yes

## Test Cases¶

• None -> TypeError
• [] -> None
• General case
timestamp  num_people  event_type
1          2           EventType.ENTER
3          1           EventType.ENTER
3          2           EventType.EXIT
7          3           EventType.ENTER
8          2           EventType.EXIT
9          2           EventType.EXIT

result = Period(7, 8)


## Algorithm¶

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.

## Code¶

In [ ]:
from enum import Enum

class Data(object):

def __init__(self, timestamp, num_people, event_type):
self.timestamp = timestamp
self.num_people = num_people
self.event_type = event_type

def __lt__(self, other):
return self.timestamp < other.timestamp

class Period(object):

def __init__(self, start, end):
self.start = start
self.end = end

def __eq__(self, other):
return self.start == other.start and self.end == other.end

def __repr__(self):
return str(self.start) + ', ' + str(self.end)

class EventType(Enum):

ENTER = 0
EXIT = 1

In [ ]:
class Solution(object):

def find_busiest_period(self, data):
# TODO: Implement me
pass


## Unit Test¶

The following unit test is expected to fail until you solve the challenge.

In [ ]:
# %load test_find_busiest_period.py
import unittest

class TestSolution(unittest.TestCase):

def test_find_busiest_period(self):
solution = Solution()
self.assertRaises(TypeError, solution.find_busiest_period, None)
self.assertEqual(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),
]
self.assertEqual(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()


## Solution Notebook¶

Review the Solution Notebook for a discussion on algorithms and code solutions.