Add tests, remove main, enhance docs in MatrixChainMultiplication (#5658)

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

@@ -0,0 +1,54 @@
+package com.thealgorithms.dynamicprogramming;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.ArrayList;
+import org.junit.jupiter.api.Test;
+
+class MatrixChainMultiplicationTest {
+
+    @Test
+    void testMatrixCreation() {
+        MatrixChainMultiplication.Matrix matrix1 = new MatrixChainMultiplication.Matrix(1, 10, 20);
+        MatrixChainMultiplication.Matrix matrix2 = new MatrixChainMultiplication.Matrix(2, 20, 30);
+
+        assertEquals(1, matrix1.count());
+        assertEquals(10, matrix1.col());
+        assertEquals(20, matrix1.row());
+
+        assertEquals(2, matrix2.count());
+        assertEquals(20, matrix2.col());
+        assertEquals(30, matrix2.row());
+    }
+
+    @Test
+    void testMatrixChainOrder() {
+        // Create a list of matrices to be multiplied
+        ArrayList<MatrixChainMultiplication.Matrix> matrices = new ArrayList<>();
+        matrices.add(new MatrixChainMultiplication.Matrix(1, 10, 20)); // A(1) = 10 x 20
+        matrices.add(new MatrixChainMultiplication.Matrix(2, 20, 30)); // A(2) = 20 x 30
+
+        // Calculate matrix chain order
+        MatrixChainMultiplication.Result result = MatrixChainMultiplication.calculateMatrixChainOrder(matrices);
+
+        // Expected cost of multiplying A(1) and A(2)
+        int expectedCost = 6000; // The expected optimal cost of multiplying A(1)(10x20) and A(2)(20x30)
+        int actualCost = result.getM()[1][2];
+
+        assertEquals(expectedCost, actualCost);
+    }
+
+    @Test
+    void testOptimalParentheses() {
+        // Create a list of matrices to be multiplied
+        ArrayList<MatrixChainMultiplication.Matrix> matrices = new ArrayList<>();
+        matrices.add(new MatrixChainMultiplication.Matrix(1, 10, 20)); // A(1) = 10 x 20
+        matrices.add(new MatrixChainMultiplication.Matrix(2, 20, 30)); // A(2) = 20 x 30
+
+        // Calculate matrix chain order
+        MatrixChainMultiplication.Result result = MatrixChainMultiplication.calculateMatrixChainOrder(matrices);
+
+        // Check the optimal split for parentheses
+        assertEquals(1, result.getS()[1][2]); // s[1][2] should point to the optimal split
+    }
+}