September 2017 Update

Task/Number-names/Kotlin/number-names.kotlin

@@ -0,0 +1,103 @@
+// version 1.1.2
+
+val names = mapOf(
+    1 to "one",
+    2 to "two",
+    3 to "three",
+    4 to "four",
+    5 to "five",
+    6 to "six",
+    7 to "seven",
+    8 to "eight",
+    9 to "nine",
+    10 to "ten",
+    11 to "eleven",
+    12 to "twelve",
+    13 to "thirteen",
+    14 to "fourteen",
+    15 to "fifteen",
+    16 to "sixteen",
+    17 to "seventeen",
+    18 to "eighteen",
+    19 to "nineteen",
+    20 to "twenty",
+    30 to "thirty",
+    40 to "forty",
+    50 to "fifty",
+    60 to "sixty",
+    70 to "seventy",
+    80 to "eighty",
+    90 to "ninety"
+)
+val bigNames = mapOf(
+    1_000L to "thousand",
+    1_000_000L to "million",
+    1_000_000_000L to "billion",
+    1_000_000_000_000L to "trillion",
+    1_000_000_000_000_000L to "quadrillion",
+    1_000_000_000_000_000_000L to "quintillion"
+)
+
+fun numToText(n: Long, uk: Boolean = false): String {
+    if (n == 0L) return "zero"
+    val neg = n < 0L
+    val maxNeg = n == Long.MIN_VALUE
+    var nn = if (maxNeg) -(n + 1) else if (neg) -n else n
+    val digits3 = IntArray(7)
+    for (i in 0..6) {  // split number into groups of 3 digits from the right
+        digits3[i] = (nn % 1000).toInt()
+        nn /= 1000
+    }
+
+    fun threeDigitsToText(number: Int) : String {
+        val sb = StringBuilder()
+        if (number == 0) return ""
+        val hundreds = number / 100
+        val remainder = number % 100
+        if (hundreds > 0) {
+            sb.append(names[hundreds], " hundred")
+            if (remainder > 0) sb.append(if (uk) " and " else " ")
+        }
+        if (remainder > 0) {
+            val tens = remainder / 10
+            val units = remainder % 10
+            if (tens > 1) {
+                sb.append(names[tens * 10])
+                if (units > 0) sb.append("-", names[units])
+            }
+            else sb.append(names[remainder])
+        }
+        return sb.toString()
+    }
+
+    val strings = Array<String>(7) { threeDigitsToText(digits3[it]) }
+    var text = strings[0]
+    var andNeeded = uk && digits3[0] in 1..99
+    var big = 1000L
+    for (i in 1..6) {
+        if (digits3[i] > 0) {
+            var text2 = strings[i] + " " + bigNames[big]
+            if (text.length > 0) {
+                text2 += if (andNeeded) " and " else ", "
+                andNeeded = false
+            }
+            else andNeeded = uk && digits3[i] in 1..99
+            text = text2 + text
+        }
+        big *= 1000
+    }
+    if (maxNeg) text = text.dropLast(5) + "eight"
+    return (if (neg) "minus " else "") + text
+}
+
+fun main(args: Array<String>) {
+    val la = longArrayOf(
+        0, 1, 7, 10, 18, 22, 67, 99, 100, 105, 999, -1056, 1000005000,
+        2074000000, 1234000000745003L, Long.MIN_VALUE
+    )
+    println("Using US representation:")
+    for (i in la) println("${"%20d".format(i)} = ${numToText(i)}")
+    println()
+    println("Using UK representation:")
+    for (i in la) println("${"%20d".format(i)} = ${numToText(i, true)}")
+}