Day 1: Standard Deviation

Day 1: Standard Deviation

import Foundation
//Day 1: Standard Deviation

func StandardDeviation(numbers: [Int]) -> Double {
    var sum = 0.0
    for eachNo in numbers {
        sum += Double(eachNo)
    }
    let mean = sum / Double(numbers.count)
    var sumOfSquare : Double = 0
    for eachNo in numbers{
        let diff  =  Double(eachNo) - mean
        let square = pow(diff, 2)
        sumOfSquare += square
    }
    let result = sqrt(sumOfSquare/Double(numbers.count))
    return result
}


//StandardDeviation(numbers: [10, 40, 30, 50, 20])

let stdout = ProcessInfo.processInfo.environment["OUTPUT_PATH"]!
FileManager.default.createFile(atPath: stdout, contents: nil, attributes: nil)
let fileHandle = FileHandle(forWritingAtPath: stdout)!

guard let n = Int((readLine()?.trimmingCharacters(in: .whitespacesAndNewlines))!)
    else { fatalError("Bad input") }

guard let arTemp = readLine() else { fatalError("Bad input") }
let ar: [Int] = arTemp.split(separator: " ").map {
    if let arItem = Int($0.trimmingCharacters(in: .whitespacesAndNewlines)) {
        return arItem
    } else { fatalError("Bad input") }
}


guard ar.count == n else { fatalError("Bad input") }
let resultvalue = StandardDeviation(numbers: ar)
let result = String(format: "%.1f", resultvalue)

fileHandle.write(String(result).data(using: .utf8)!)
fileHandle.write("\n".data(using: .utf8)!)