fibonacci

jeorg-kotlin-crums/jeorg-kotlin-crums-4-variance/pom.xml

@@ -35,6 +35,14 @@
             <artifactId>mockk</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>io.kotest</groupId>
+            <artifactId>kotest-assertions-api-jvm</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.kotest</groupId>
+            <artifactId>kotest-assertions-core-jvm</artifactId>
+        </dependency>
     </dependencies>
 
     <build>

jeorg-kotlin-crums/jeorg-kotlin-crums-4-variance/src/main/kotlin/org/jesperancinha/ktd/Main.kt

@@ -11,6 +11,7 @@ class Main {
             ImmutableEatingOut.main()
             CupManager.main()
             Patisserie.main()
+            WarehouseManager.main()
         }
     }
 }

jeorg-kotlin-crums/jeorg-kotlin-crums-4-variance/src/main/kotlin/org/jesperancinha/ktd/TailRec.kt

@@ -0,0 +1,27 @@
+package org.jesperancinha.ktd
+
+class TailRec {
+    companion object {
+        @JvmStatic
+        fun main(args: Array<String> = emptyArray()) {
+            println(fibonnaci(5))
+            println(fibonnaciOptimized(5))
+        }
+
+        fun fibonnaci(value: Int): Int {
+            if (value == 2) return 1
+            if (value == 1) return 0
+            return fibonnaci(value - 1) +
+                    fibonnaci(value - 2)
+        }
+
+        tailrec fun fibonnaciOptimized(value: Int,
+                                       curr: Int = 1,
+                                       sum: Int = 0): Int {
+            if (value == 1)
+                return sum
+            return fibonnaciOptimized(value - 1,
+                    sum, sum + curr)
+        }
+    }
+}

jeorg-kotlin-crums/jeorg-kotlin-crums-4-variance/src/test/kotlin/org/jesperancinha/ktd/TailRecTest.kt

@@ -0,0 +1,45 @@
+package org.jesperancinha.ktd
+
+import io.kotest.matchers.shouldBe
+import org.jesperancinha.ktd.TailRec.Companion.fibonnaci
+import org.jesperancinha.ktd.TailRec.Companion.fibonnaciOptimized
+import kotlin.test.Test
+
+class TailRecTest {
+
+    @Test
+    fun `should calculate 1 element fibonacci`() {
+        fibonnaci(1) shouldBe 0
+        fibonnaciOptimized(1) shouldBe 0
+    }
+
+    @Test
+    fun `should calculate 2 element fibonacci`() {
+        fibonnaci(2) shouldBe 1
+        fibonnaciOptimized(2) shouldBe 1
+    }
+
+    @Test
+    fun `should calculate 3 element fibonacci`() {
+        fibonnaci(3) shouldBe 1
+        fibonnaciOptimized(3) shouldBe 1
+    }
+
+    @Test
+    fun `should calculate 4 element fibonacci`() {
+        fibonnaci(4) shouldBe 2
+        fibonnaciOptimized(4) shouldBe 2
+    }
+
+    @Test
+    fun `should calculate 5 element fibonacci`() {
+        fibonnaci(5) shouldBe 3
+        fibonnaciOptimized(5) shouldBe 3
+    }
+
+    @Test
+    fun `should calculate 9 element fibonacci`() {
+        fibonnaci(9) shouldBe 21
+        fibonnaciOptimized(9) shouldBe 21
+    }
+}