Improve docs, remove main, add tests for `MatrixChainRecursiveTopDo… (#5659)

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

@@ -0,0 +1,68 @@
+package com.thealgorithms.dynamicprogramming;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+class MatrixChainRecursiveTopDownMemoisationTest {
+
+    /**
+     * Test case for four matrices with dimensions 1x2, 2x3, 3x4, and 4x5.
+     * The expected minimum number of multiplications is 38.
+     */
+    @Test
+    void testFourMatrices() {
+        int[] dimensions = {1, 2, 3, 4, 5};
+        int expected = 38;
+        int actual = MatrixChainRecursiveTopDownMemoisation.memoizedMatrixChain(dimensions);
+        assertEquals(expected, actual, "The minimum number of multiplications should be 38.");
+    }
+
+    /**
+     * Test case for three matrices with dimensions 10x20, 20x30, and 30x40.
+     * The expected minimum number of multiplications is 6000.
+     */
+    @Test
+    void testThreeMatrices() {
+        int[] dimensions = {10, 20, 30, 40};
+        int expected = 18000;
+        int actual = MatrixChainRecursiveTopDownMemoisation.memoizedMatrixChain(dimensions);
+        assertEquals(expected, actual, "The minimum number of multiplications should be 18000.");
+    }
+
+    /**
+     * Test case for two matrices with dimensions 5x10 and 10x20.
+     * The expected minimum number of multiplications is 1000.
+     */
+    @Test
+    void testTwoMatrices() {
+        int[] dimensions = {5, 10, 20};
+        int expected = 1000;
+        int actual = MatrixChainRecursiveTopDownMemoisation.memoizedMatrixChain(dimensions);
+        assertEquals(expected, actual, "The minimum number of multiplications should be 1000.");
+    }
+
+    /**
+     * Test case for a single matrix.
+     * The expected minimum number of multiplications is 0, as there are no multiplications needed.
+     */
+    @Test
+    void testSingleMatrix() {
+        int[] dimensions = {10, 20}; // Single matrix dimensions
+        int expected = 0;
+        int actual = MatrixChainRecursiveTopDownMemoisation.memoizedMatrixChain(dimensions);
+        assertEquals(expected, actual, "The minimum number of multiplications should be 0.");
+    }
+
+    /**
+     * Test case for matrices with varying dimensions.
+     * The expected minimum number of multiplications is calculated based on the dimensions provided.
+     */
+    @Test
+    void testVaryingDimensions() {
+        int[] dimensions = {2, 3, 4, 5, 6}; // Dimensions for 4 matrices
+        int expected = 124; // Expected value needs to be calculated based on the problem
+        int actual = MatrixChainRecursiveTopDownMemoisation.memoizedMatrixChain(dimensions);
+        assertEquals(expected, actual, "The minimum number of multiplications should be 124.");
+    }
+}