Pairwise twice speedy solution for Changing direction by amandel - python coding challenges

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Pairwise twice solution in Speedy category for Changing direction by amandel

from itertools import pairwise
def changing_direction(e: list) -> int:
    return sum(x*y<0 for x,y in pairwise(x-y for x,y in pairwise(e) if x!=y))

print("Example:")
print(changing_direction([1, 2, 3, 4, 5]))

assert changing_direction([1, 2, 3, 4, 5]) == 0
assert changing_direction([1, 2, 3, 2, 1]) == 1
assert changing_direction([1, 2, 2, 1, 2, 2]) == 2

print("The mission is done! Click 'Check Solution' to earn rewards!")

Aug. 20, 2022

Comments:

rybld2 on Sept. 27, 2022, 10:55 a.m.
simply great! This python is fantastic!

arthur.antonoff on Jan. 15, 2024, 3:29 p.m.
Very nice! Great use of x*y for verify when x and y are just in different directions

mmartsinenko on Dec. 7, 2024, 10:42 p.m.
This pairwise-based solution is impressively compact, and leverages advanced Python features like nested comprehensions and itertools.pairwise. It calculates changes in direction efficiently by directly comparing consecutive differences. I’m particularly interested in this approach, as it’s faster than my current solution. However, the dense syntax may be challenging for beginners to grasp. Excellent work showcasing an elegant and high-performance alternative!

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