Find minimum laptop a school needs to rent out to students

laptopRental.py

# you're given a list of time intervals during which students at a school need a laptop. 
# These time intervals are represented by pairs of integers [start, end], where 0 <= start < end. 
# However, start and end don't represent real times; therefore, they may be greater than 24. 
# No two students can use a laptop at the same time, but immediately after a student is done 
# using a laptop, another student can use that same laptop. For example, if one student rents a 
# laptop during the time interval [0, 2], another student can rent the same laptop during any 
# time interval starting with 2. Write a function that returns the minimum number of laptops 
# that the school needs to rent such that all students will always have access to a laptop when 
# they need one. laptopRentals(times) 
# Parameters times: Array (of Array (of Integers)) - A 2D array containing the times the 
# student would require a laptop. 
# Return Value Integer - Minimum number of laptops the school needs to rent. 
# Examples times Return Value 
# [[0,2],[1,4],[4,6],[0,4],[7,8],[9,11],[3,10]] 3 
# [[0,4],[2,3],[2,3],[2,3]] 4 
# [[1,5],[5,6],[6,7],[7,9]] 1


def laptopRentals(times):
    events = []
    times.sort()
    for t in times:
        events.append(('start',t[0]))
        events.append(('end',t[1]))
    events.sort(key=lambda x: x[1])
    laptops_in_use = 0
    max_in_use = 0
    for event in events:
        if event[0] == 'start':
            laptops_in_use += 1
            max_in_use = max(max_in_use, laptops_in_use)
        if event[0] == 'end':
            laptops_in_use -= 1
    return max_in_use
print(laptop_rentals([[0,2],[1,4],[4,6],[0,4],[7,8],[9,11],
[3,10]])) 

Is this 2N?

times need to be sorted first to ensure algorithm works correctly.