[juggler-sequence] juggler seq

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/jugglersequence/JugglerSequenceUnitTest.java

@@ -0,0 +1,68 @@
+package com.baeldung.algorithms.jugglersequence;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+class JugglerSequenceGenerator {
+
+    public static List<Integer> byLoop(int n) {
+        if (n <= 0) {
+            throw new IllegalArgumentException("The initial integer must be greater than zero.");
+        }
+        List<Integer> seq = new ArrayList<>();
+        int current = n;
+        seq.add(current);
+        while (current != 1) {
+            int next = (int) (Math.sqrt(current) * (current % 2 == 0 ? 1 : current));
+            seq.add(next);
+            current = next;
+        }
+        return seq;
+    }
+
+    public static List<Integer> byRecursion(int n) {
+        if (n <= 0) {
+            throw new IllegalArgumentException("The initial integer must be greater than zero.");
+        }
+        List<Integer> seq = new ArrayList<>();
+        fillSeqRecursively(n, seq);
+        return seq;
+    }
+
+    private static void fillSeqRecursively(int current, List<Integer> result) {
+        result.add(current);
+        if (current == 1) {
+            return;
+        }
+        int next = (int) (Math.sqrt(current) * (current % 2 == 0 ? 1 : current));
+        fillSeqRecursively(next, result);
+    }
+}
+
+public class JugglerSequenceUnitTest {
+
+    @Test
+    void whenGeneratingJugglerSeqUsingLoop_thenGetTheExpectedResult() {
+        assertThrows(IllegalArgumentException.class, () -> JugglerSequenceGenerator.byLoop(0));
+        assertEquals(List.of(3, 5, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byLoop(3));
+        assertEquals(List.of(4, 2, 1), JugglerSequenceGenerator.byLoop(4));
+        assertEquals(List.of(9, 27, 140, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byLoop(9));
+        assertEquals(List.of(21, 96, 9, 27, 140, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byLoop(21));
+        assertEquals(List.of(42, 6, 2, 1), JugglerSequenceGenerator.byLoop(42));
+    }
+
+    @Test
+    void whenGeneratingJugglerSeqUsingRecursion_thenGetTheExpectedResult() {
+        assertThrows(IllegalArgumentException.class, () -> JugglerSequenceGenerator.byRecursion(0));
+        assertEquals(List.of(3, 5, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byRecursion(3));
+        assertEquals(List.of(4, 2, 1), JugglerSequenceGenerator.byRecursion(4));
+        assertEquals(List.of(9, 27, 140, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byRecursion(9));
+        assertEquals(List.of(21, 96, 9, 27, 140, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byRecursion(21));
+        assertEquals(List.of(42, 6, 2, 1), JugglerSequenceGenerator.byRecursion(42));
+    }
+}