Algorithms/JavaAlgorithms
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

refactor: cleanup EulersFunction (#5388)

Browse Source
This commit is contained in:
Alex Klymenko 2024-08-25 21:44:55 +02:00 committed by GitHub
parent f3851e3adc
commit 25b8010ea8
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
2 changed files with 35 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
src/main/java/com/thealgorithms/others/EulersFunction.java
View File

@ -1,12 +1,19 @@
package com.thealgorithms.others;
/**
* @brief utility class for <a href="https://en.wikipedia.org/wiki/Euler%27s_totient_function">Euler's totient function</a>
* Utility class for computing
* <a href="https://en.wikipedia.org/wiki/Euler%27s_totient_function">Euler's totient function</a>.
*/
public final class EulersFunction {
private EulersFunction() {
}
/**
* Validates that the input is a positive integer.
*
* @param n the input number to validate
* @throws IllegalArgumentException if {@code n} is non-positive
*/
private static void checkInput(int n) {
if (n <= 0) {
throw new IllegalArgumentException("n must be positive.");
@ -14,11 +21,12 @@ public final class EulersFunction {
}
/**
* @brief computes the value of Euler's totient function for given input
* @details has time complexity of O(sqrt(n))
* @param n the input
* @exception IllegalArgumentException n is non-positive
* @return the value of Euler's totient function for the input
* Computes the value of Euler's totient function for a given input.
* This function has a time complexity of O(sqrt(n)).
*
* @param n the input number
* @return the value of Euler's totient function for the given input
* @throws IllegalArgumentException if {@code n} is non-positive
*/
public static int getEuler(int n) {
checkInput(n);

48
src/test/java/com/thealgorithms/others/EulersFunctionTest.java
View File

@ -3,37 +3,31 @@ package com.thealgorithms.others;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;
import java.util.HashMap;
import org.junit.jupiter.api.Test;
import java.util.stream.Stream;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;
class EulersFunctionTest {
@Test
public void testGetEuler() {
HashMap<Integer, Integer> testCases = new HashMap<>();
testCases.put(1, 1);
testCases.put(2, 1);
testCases.put(3, 2);
testCases.put(4, 2);
testCases.put(5, 4);
testCases.put(6, 2);
testCases.put(10, 4);
testCases.put(21, 12);
testCases.put(69, 44);
testCases.put(47, 46);
testCases.put(46, 22);
testCases.put(55, 40);
testCases.put(34, 16);
testCases.put(20, 8);
testCases.put(20, 8);
testCases.put(1024, 512);
for (final var tc : testCases.entrySet()) {
assertEquals(tc.getValue(), EulersFunction.getEuler(tc.getKey()));
}
@ParameterizedTest
@MethodSource("provideNumbersForGetEuler")
void testGetEuler(int input, int expected) {
assertEquals(expected, EulersFunction.getEuler(input));
}
@Test
public void testGetEulerThrowsExceptionForNonPositiveInput() {
assertThrows(IllegalArgumentException.class, () -> EulersFunction.getEuler(0));
@ParameterizedTest
@MethodSource("provideInvalidNumbersForGetEuler")
void testGetEulerThrowsExceptionForNonPositiveInput(int input) {
assertThrows(IllegalArgumentException.class, () -> EulersFunction.getEuler(input));
}
private static Stream<Arguments> provideNumbersForGetEuler() {
return Stream.of(Arguments.of(1, 1), Arguments.of(2, 1), Arguments.of(3, 2), Arguments.of(4, 2), Arguments.of(5, 4), Arguments.of(6, 2), Arguments.of(10, 4), Arguments.of(21, 12), Arguments.of(69, 44), Arguments.of(47, 46), Arguments.of(46, 22), Arguments.of(55, 40), Arguments.of(34, 16),
Arguments.of(20, 8), Arguments.of(1024, 512));
}
private static Stream<Arguments> provideInvalidNumbersForGetEuler() {
return Stream.of(Arguments.of(0), Arguments.of(-1), Arguments.of(-10));
}
}