Swift running sum

Question

I\'d like a function runningSum on an array of numbers a (or any ordered collection of addable things) that returns an array of the same length where each eleme

Answer 1

One solution using reduce:

func runningSum(array: [Int]) -> [Int] {
    return array.reduce([], combine: { (result: [Int], item: Int) -> [Int] in
        if result.isEmpty {
            return [item] //first item, just take the value
        }

        // otherwise take the previous value and append the new item
        return result + [result.last! + item]
    })
}