def sum_in(numbers, sum_):
"""whether any two numbers from `numbers` form `sum_`."""
return any((sum_-n) in numbers for n in numbers)
It basically takes a list, and checks if any two numbers from it form a sum equalling sum_. I can't seem to get how that sum_-n verifies that TWO numbers equal the sum. Wouldn't it just be checking with one n each loop?!
It's checking sum_-n is in numbers. If it is, then that number + n = sum_.
For each iteration, a bool is generated whether (sum_ - n) is in the set of numbers. If one of these bools is True, the function returns True. It returns False otherwise, clearly.
This is not a great algorithm, to put it mildly.
Consider:
sum_in((3,), 6)
This will return True. Why? Because 6 - 3 is in numbers.
So yes, it is only checking one value in each iteration.
Good luck with the interview!
