Solution.swift

Solution.swift

import Foundation

// Complete the longestSequence function below.
/// Finds the largest prime divisor
func findLargestDivisor(for number: Int)-> Int {
    let maxInt = Int(sqrt(Double(number)).rounded(.up) + 1)
        for possibleDivisor in 2..<maxInt{
            if number % possibleDivisor == 0 {
                return number / possibleDivisor
            }
        }
        return 1
}

func getMaxMoves(for number: Int) -> Int {
    var movesCount = 0
    var replacementNumber = number
    // finding the largest divisor and replacing each iteration.
    // largest divisor gives you the amount of moves at each iteration in reverse.
    while replacementNumber > 1 {
 // 2, 2, 2, 3
        let largestDivisor = findLargestDivisor(for: replacementNumber) // 12, 6, 3, 1
        replacementNumber = largestDivisor
        movesCount += largestDivisor
    }
    movesCount += number
    // can be verified by storing the smallest divisors (largest/replacementnumber) at each iteration and splitting into the amount of each smallest divisor start with the last one and working backwards
    return movesCount
}

func longestSequence(a: [Int]) -> Int {
    // Return the length of the longest possible sequence of moves.
    return a.map(getMaxMoves(for:)).reduce(0, +)
}
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 aTemp = readLine() else { fatalError("Bad input") }
let a: [Int] = aTemp.split(separator: " ").map {
    if let aItem = Int($0.trimmingCharacters(in: .whitespacesAndNewlines)) {
        return aItem
    } else { fatalError("Bad input") }
}

guard a.count == n else { fatalError("Bad input") }

let result = longestSequence(a: a)

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