ios - How to add numbers using multiple threads?

Question

I'm trying to add the numbers in a range eg. 1 to 50000000. But using a for-loop or reduce(_:_:) is taking too long to calculate the result.

func add(low: Int, high: Int) -> Int {
    return (low...high).reduce(0, +)
}

Is there any way to do it using multiple threads?

question from:https://stackoverflow.com/questions/65931618/how-to-add-numbers-using-multiple-threads

Answer 1

If you want a function to just return the sum to all integers in range from low to high then you can do it even faster with some simple maths

you can consider an arithmetic sequence starting from low and going to high with a common difference of 1 ,and have (high - low + 1) elements in it.

then the sum will straight up be :-

sum = ( (high * ( high + 1 )) - ((low * (low - 1)) ) / 2