Print English Names

gistfile1.swift

import Foundation

func convertToEnglish(number: Int) -> (Int, String) {

    let unitsMap = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"]
    let tensMap = ["zero", "ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"]
    let denom = [ "", " hundred", " thousand", "", " hundred", " million", "", " hundred", " billion"]

    if number == 0 {
        return (number, unitsMap[number])
    }

    var digits: [Int] = []
    var num = number

    while num > 0 {
        digits += [num % 10]
        num = num / 10
    }

    func group(ones: Int, tens: Int) -> [String] {
        let first2 = ones + (tens * 10)
        var arr: [String] = []
        if first2 == 0 {
            arr += [""]
        } else if first2 < 20 {
            arr += [unitsMap[first2]]
        } else {
            arr += [unitsMap[ones]]
            arr += [tensMap[tens]]
        }
        return arr
    }

    digits = digits.reversed()
    var resultArr: [String] = []
    repeat {
        let ones = digits.popLast() ?? 0
        let tens = digits.popLast() ?? 0
        resultArr += group(ones: ones, tens: tens)
        if let hundreds = digits.popLast() {
            resultArr += [hundreds == 0 ? "" : unitsMap[hundreds]]
        }
   } while !digits.isEmpty

    let mappedResults = zip(resultArr, denom)
    let result = mappedResults.reversed().reduce("") {
        $0 + ($1.0 == unitsMap[0] ? "" : $1.0) + ($1.0.isEmpty ? "" : $1.1) + " "
    }
    return (number, result.trimmingCharacters(in: .whitespaces))
}

Swift.print(convertToEnglish(number: 54_443_000))
Swift.print(convertToEnglish(number: 5_443_213))
Swift.print(convertToEnglish(number: 5_443_000))
Swift.print(convertToEnglish(number: 5_440_000))
Swift.print(convertToEnglish(number: 429_100))
Swift.print(convertToEnglish(number: 42_900))
Swift.print(convertToEnglish(number: 42_200))
Swift.print(convertToEnglish(number: 42_000))
Swift.print(convertToEnglish(number: 2_414))
Swift.print(convertToEnglish(number: 2_000))
Swift.print(convertToEnglish(number: 110))
Swift.print(convertToEnglish(number: 100))
Swift.print(convertToEnglish(number: 114))
Swift.print(convertToEnglish(number: 1))
Swift.print(convertToEnglish(number: 0))

(54443000, "fifty four million four hundred forty three thousand")
(5443213, "five million four hundred forty three thousand two hundred thirteen")
(5443000, "five million four hundred forty three thousand")
(5440000, "five million four hundred forty thousand")
(429100, "four hundred twenty nine thousand one hundred")
(42900, "forty two thousand nine hundred")
(42200, "forty two thousand two hundred")
(42000, "forty two thousand")
(2414, "two thousand four hundred fourteen")
(2000, "two thousand")
(110, "one hundred ten")
(100, "one hundred")
(114, "one hundred fourteen")
(1, "one")
(0, "zero")