refactor(matrix): Improve code readability and error handling in determinant calculation

Author: Rony-2004

src/main/java/com/thealgorithms/matrix/MatrixDeterminant.java

@@ -21,6 +21,9 @@
 package com.thealgorithms.matrix;
 
 public class MatrixDeterminant {
+    private MatrixDeterminant() {
+        throw new AssertionError("Utility class");
+    }
 
     public static double determinant(double[][] m) {
         int n = m.length;
@@ -29,29 +32,43 @@ public static double determinant(double[][] m) {
                 throw new IllegalArgumentException("Matrix must be square");
             }
         }
-        if (n == 1) return m[0][0];
-        if (n == 2) return m[0][0]*m[1][1] - m[0][1]*m[1][0];
+        if (n == 1) {
+            return m[0][0];
+        }
+
+        if (n == 2) {
+            return m[0][0] * m[1][1] - m[0][1] * m[1][0];
+        }
 
         double det = 0;
         for (int c = 0; c < n; c++) {
             det += Math.pow(-1, c) * m[0][c] * determinant(minor(m, 0, c));
         }
+
         return det;
     }
 
     private static double[][] minor(double[][] m, int row, int col) {
         int n = m.length;
-        double[][] min = new double[n-1][n-1];
+        double[][] min = new double[n - 1][n - 1];
         int r = 0;
         for (int i = 0; i < n; i++) {
-            if (i == row) continue;
+            if (i == row) {
+                continue;
+            }
+
             int c = 0;
             for (int j = 0; j < n; j++) {
-                if (j == col) continue;
+                if (j == col) {
+                    continue;
+                }
+
                 min[r][c++] = m[i][j];
             }
+
             r++;
         }
+
         return min;
     }
 }

src/test/java/com/thealgorithms/matrix/MatrixDeterminantTest.java

@@ -1,7 +1,8 @@
 package com.thealgorithms.matrix;
 
 import org.junit.jupiter.api.Test;
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 class MatrixDeterminantTest {