September 2017 Update

Task/Exponentiation-operator/Kotlin/exponentiation-operator.kotlin

@@ -0,0 +1,43 @@
+// version 1.0.6
+
+infix fun Int.ipow(exp: Int): Int =
+    when {
+        this ==  1 -> 1
+        this == -1 -> if (exp % 2 == 0) 1 else -1
+        exp <  0   -> throw IllegalArgumentException("invalid exponent")
+        exp == 0   -> 1
+        else       -> {
+            var ans = 1
+            var base = this
+            var e = exp
+            while (e > 0) {
+                if (e and 1 == 1) ans *= base
+                e = e shr 1
+                base *= base
+            }
+            ans
+        }
+    }
+
+infix fun Double.dpow(exp: Int): Double {
+    var ans = 1.0
+    var e   = exp
+    var base = if (e < 0) 1.0 / this else this
+    if (e < 0) e = -e
+    while (e > 0) {
+        if (e and 1 == 1) ans *= base
+        e = e shr 1
+        base *= base
+    }
+    return ans
+}
+
+fun main(args: Array<String>) {
+    println("2  ^ 3   = ${2 ipow 3}")
+    println("1  ^ -10 = ${1 ipow -10}")
+    println("-1 ^ -3  = ${-1 ipow -3}")
+    println()
+    println("2.0 ^ -3 = ${2.0 dpow -3}")
+    println("1.5 ^ 0  = ${1.5 dpow 0}")
+    println("4.5 ^ 2  = ${4.5 dpow 2}")
+}