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Refactor factorial, add unit tests (#4266)
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@ -1,15 +1,6 @@
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package com.thealgorithms.maths;
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public class Factorial {
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/* Driver Code */
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public static void main(String[] args) {
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assert factorial(0) == 1;
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assert factorial(1) == 1;
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assert factorial(5) == 120;
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assert factorial(10) == 3628800;
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}
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/**
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* Calculate factorial N using iteration
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*
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@ -18,11 +9,12 @@ public class Factorial {
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*/
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public static long factorial(int n) {
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if (n < 0) {
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throw new IllegalArgumentException("number is negative");
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throw new IllegalArgumentException("Input number cannot be negative");
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}
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long factorial = 1;
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for (int i = 1; i <= n; factorial *= i, ++i)
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;
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for (int i = 1; i <= n; ++i) {
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factorial *= i;
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}
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return factorial;
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}
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}
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@ -5,9 +5,19 @@ import static org.junit.jupiter.api.Assertions.*;
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import org.junit.jupiter.api.Test;
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public class FactorialTest {
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private static final String EXCEPTION_MESSAGE = "Input number cannot be negative";
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@Test
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public void test() {
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public void testWhenInvalidInoutProvidedShouldThrowException() {
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IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> Factorial.factorial(-1));
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assertEquals(exception.getMessage(), EXCEPTION_MESSAGE);
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}
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@Test
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public void testCorrectFactorialCalculation() {
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assertEquals(1, Factorial.factorial(0));
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assertEquals(1, Factorial.factorial(1));
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assertEquals(120, Factorial.factorial(5));
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assertEquals(3628800, Factorial.factorial(10));
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}
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}
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