diff --git a/src/main/java/com/thealgorithms/maths/Factorial.java b/src/main/java/com/thealgorithms/maths/Factorial.java index 511cc1f84f05..8ad219a3066c 100644 --- a/src/main/java/com/thealgorithms/maths/Factorial.java +++ b/src/main/java/com/thealgorithms/maths/Factorial.java @@ -1,23 +1,19 @@ package com.thealgorithms.maths; +import java.math.BigInteger; + public final class Factorial { private Factorial() { } - /** - * Calculate factorial N using iteration - * - * @param n the number - * @return the factorial of {@code n} - */ - public static long factorial(int n) { + public static BigInteger factorial(int n) { if (n < 0) { throw new IllegalArgumentException("Input number cannot be negative"); } - long factorial = 1; - for (int i = 1; i <= n; ++i) { - factorial *= i; + BigInteger result = BigInteger.ONE; + for (int i = 1; i <= n; i++) { + result = result.multiply(BigInteger.valueOf(i)); } - return factorial; + return result; } } diff --git a/src/test/java/com/thealgorithms/maths/FactorialTest.java b/src/test/java/com/thealgorithms/maths/FactorialTest.java index 3ff7097b8113..a393136696e1 100644 --- a/src/test/java/com/thealgorithms/maths/FactorialTest.java +++ b/src/test/java/com/thealgorithms/maths/FactorialTest.java @@ -3,6 +3,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals; import static org.junit.jupiter.api.Assertions.assertThrows; +import java.math.BigInteger; import org.junit.jupiter.api.Test; public class FactorialTest { @@ -16,9 +17,9 @@ public void testWhenInvalidInoutProvidedShouldThrowException() { @Test public void testCorrectFactorialCalculation() { - assertEquals(1, Factorial.factorial(0)); - assertEquals(1, Factorial.factorial(1)); - assertEquals(120, Factorial.factorial(5)); - assertEquals(3628800, Factorial.factorial(10)); + assertEquals(BigInteger.ONE, Factorial.factorial(0)); + assertEquals(BigInteger.ONE, Factorial.factorial(1)); + assertEquals(BigInteger.valueOf(120), Factorial.factorial(5)); + assertEquals(BigInteger.valueOf(3628800), Factorial.factorial(10)); } }