@swift-5.3.3 -O
import Foundation func measure(_ body: () -> Void) { let start = Date.timeIntervalSinceReferenceDate for _ in 0 ..< 10 { body() } let end = Date.timeIntervalSinceReferenceDate print((end - start) / 10) } public func sumOfEvensByStride(_ n: Int) -> Int { var sum = 0 for m in stride(from: 0, through: n * 2, by: 2) { sum &+= m } return sum } public func sumOfEvensByRange(_ n: Int) -> Int { var sum = 0 for m in 0 ... n { sum &+= m * 2 } return sum } public func sumOfMultiplesByStride(_ n: Int, k: Int) -> Int { var sum = 0 for m in stride(from: 0, through: n * k, by: k) { sum &+= m } return sum } public func sumOfMultiplesByRange(_ n: Int, k: Int) -> Int { var sum = 0 for m in 0 ... n { sum &+= m * k } return sum } let n = 100_000_000 + (1 ... 100).randomElement()! var a = 0 measure { a &+= sumOfEvensByStride(n) } measure { a &+= sumOfEvensByRange(n) } measure { a &+= sumOfMultiplesByStride(n, k: 3) } measure { a &+= sumOfMultiplesByRange(n, k: 3) } print(a)