Add Tribonacci Numbers (fixes #4646) (#4959)

src/test/java/com/thealgorithms/dynamicprogramming/TribonacciTest.java

@@ -0,0 +1,24 @@
+package com.thealgorithms.dynamicprogramming;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Test class for {@code Tribonacci}.
+ */
+public class TribonacciTest {
+
+    /**
+     * Tests the Tribonacci computation for a set of known values.
+     */
+    @Test
+    public void testKnownValues() {
+        assertEquals(0, Tribonacci.compute(0), "The 0th Tribonacci should be 0.");
+        assertEquals(1, Tribonacci.compute(1), "The 1st Tribonacci should be 1.");
+        assertEquals(1, Tribonacci.compute(2), "The 2nd Tribonacci should be 1.");
+        assertEquals(2, Tribonacci.compute(3), "The 3rd Tribonacci should be 2.");
+        assertEquals(4, Tribonacci.compute(4), "The 4th Tribonacci should be 4.");
+        assertEquals(7, Tribonacci.compute(5), "The 5th Tribonacci should be 7.");
+    }
+}