Fixed Issue DmitryTsyvtsyn#5 - Factorial loop can be start from 2

Author: Dmitry

gradlew.bat

@@ -1,4 +1,4 @@
-@rem
+git @rem
 @rem Copyright 2015 the original author or authors.
 @rem
 @rem Licensed under the Apache License, Version 2.0 (the "License");

src/main/kotlin/other/Factorial.kt

@@ -14,8 +14,12 @@ class Factorial {
      * @return returns the factorial of a number by an iterative method
      */
     fun compute(number: Int) : Int {
+        if (number <= 1) {
+            return 1
+        }
+
         var result = 1
-        for (i in 1..number) {
+        for (i in 2..number) {
            result *= i
         }
         return result
@@ -25,6 +29,7 @@ class Factorial {
      * worst time: O(n)
      * amount of memory: O(n) - stack for recursion
      *
+     * @return returns factorial recursively
      */
     fun computeRecursive(number: Int) : Int {
         return if (number <= 1) {

src/test/kotlin/other/FactorialTest.kt

@@ -9,13 +9,17 @@ internal class FactorialTest {
 
     @Test
     fun test_iterative() {
+        assertEquals(1, factorial.compute(0))
+        assertEquals(1, factorial.compute(1))
         assertEquals(6, factorial.compute(3))
         assertEquals(120, factorial.compute(5))
         assertEquals(720, factorial.compute(6))
     }
 
     @Test
     fun test_recursive() {
+        assertEquals(1, factorial.compute(0))
+        assertEquals(1, factorial.compute(1))
         assertEquals(6, factorial.computeRecursive(3))
         assertEquals(120, factorial.computeRecursive(5))
         assertEquals(720, factorial.computeRecursive(6))