perfect-numbers: add to track

config.json

@@ -61,7 +61,8 @@
     "clock",
     "diamond",
     "secret-handshake",
-    "flatten-array"
+    "flatten-array",
+    "perfect-numbers"
   ],
   "exercises": [
     {
@@ -353,6 +354,11 @@
       "slug": "flatten-array",
       "difficulty": 1,
       "topics": []
+    },
+    {
+      "slug": "perfect-numbers",
+      "difficulty": 1,
+      "topics": []
     }
   ],
   "deprecated": [

exercises/perfect-numbers/build.gradle

@@ -0,0 +1,17 @@
+apply plugin: "java"
+apply plugin: "eclipse"
+apply plugin: "idea"
+
+repositories {
+  mavenCentral()
+}
+
+dependencies {
+  testCompile "junit:junit:4.12"
+}
+test {
+  testLogging {
+    exceptionFormat = 'full'
+    events = ["passed", "failed", "skipped"]
+  }
+}

exercises/perfect-numbers/src/example/java/Classification.java

@@ -0,0 +1 @@
+../../main/java/Classification.java

exercises/perfect-numbers/src/example/java/NaturalNumber.java

@@ -0,0 +1,30 @@
+import java.util.stream.IntStream;
+
+final class NaturalNumber {
+
+    private final int naturalNumber;
+
+    NaturalNumber(int naturalNumber) {
+        if (naturalNumber <= 0) throw new IllegalStateException("Natural numbers are all positive.");
+        this.naturalNumber = naturalNumber;
+    }
+
+    Classification getClassification() {
+        final int aliquotSum = computeAliquotSum();
+
+        if (aliquotSum == naturalNumber) {
+            return Classification.PERFECT;
+        } else if (aliquotSum > naturalNumber) {
+            return Classification.ABUNDANT;
+        } else {
+            return Classification.DEFICIENT;
+        }
+    }
+
+    private int computeAliquotSum() {
+        return IntStream.range(1, naturalNumber)
+                .filter(it -> naturalNumber % it == 0)
+                .sum();
+    }
+
+}

exercises/perfect-numbers/src/main/java/Classification.java

@@ -0,0 +1,5 @@
+enum Classification {
+
+    DEFICIENT, PERFECT, ABUNDANT
+
+}

exercises/perfect-numbers/src/main/java/NaturalNumber.java

@@ -0,0 +1,5 @@
+final class NaturalNumber {
+
+
+
+}

exercises/perfect-numbers/src/test/java/NaturalNumberTest.java

@@ -0,0 +1,61 @@
+import org.junit.Ignore;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public final class NaturalNumberTest {
+
+    @Test
+    public void testSmallPerfectNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.PERFECT, new NaturalNumber(6).getClassification());
+    }
+
+    @Ignore
+    @Test
+    public void testMediumPerfectNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.PERFECT, new NaturalNumber(28).getClassification());
+    }
+
+    @Ignore
+    @Test
+    public void testLargePerfectNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.PERFECT, new NaturalNumber(33550336).getClassification());
+    }
+
+    @Ignore
+    @Test
+    public void testSmallAbundantNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.ABUNDANT, new NaturalNumber(12).getClassification());
+    }
+
+    @Ignore
+    @Test
+    public void testMediumAbundantNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.ABUNDANT, new NaturalNumber(24).getClassification());
+    }
+
+    @Ignore
+    @Test
+    public void testLargeAbundantNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.ABUNDANT, new NaturalNumber(33550335).getClassification());
+    }
+
+    @Ignore
+    @Test
+    public void testSmallDeficientNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.DEFICIENT, new NaturalNumber(8).getClassification());
+    }
+
+    @Ignore
+    @Test
+    public void testMediumNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.DEFICIENT, new NaturalNumber(31).getClassification());
+    }
+
+    @Ignore
+    @Test
+    public void testLargeDeficientNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.DEFICIENT, new NaturalNumber(33550337).getClassification());
+    }
+
+}

exercises/settings.gradle

@@ -34,6 +34,7 @@ include 'octal'
 include 'palindrome-products'
 include 'pangram'
 include 'pascals-triangle'
+include 'perfect-numbers'
 include 'phone-number'
 include 'pig-latin'
 include 'prime-factors'