BAEL-2504 Combinations

Initial Combinations code.

algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/combination/CombinationUnitTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.algorithms.combination;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.List;
+
+import org.junit.Test;
+
+public class CombinationUnitTest {
+
+    private static final int N = 5;
+    private static final int R = 3;
+    private static final int nCr = 10;
+      
+    @Test
+    public void givenSetAndSelectionSize_whenCalculatedUsingSetRecursiveAlgorithm_thenExpectedCount() {
+        SetRecursiveCombinationGenerator generator = new SetRecursiveCombinationGenerator();
+        List<int[]> selection = generator.generate(N, R);
+        assertEquals(nCr, selection.size());
+    }
+
+    @Test
+    public void givenSetAndSelectionSize_whenCalculatedUsingSelectionRecursiveAlgorithm_thenExpectedCount() {
+        SelectionRecursiveCombinationGenerator generator = new SelectionRecursiveCombinationGenerator();
+        List<int[]> selection = generator.generate(N, R);
+        assertEquals(nCr, selection.size());
+    }
+    
+    @Test
+    public void givenSetAndSelectionSize_whenCalculatedUsingIterativeAlgorithm_thenExpectedCount() {
+        IterativeCombinationGenerator generator = new IterativeCombinationGenerator();
+        List<int[]> selection = generator.generate(N, R);
+        assertEquals(nCr, selection.size());
+    }
+}