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BAEL-7598 Check if a number is a perfect number (#16039) 

* BAEL-7598 Check if a number is a perfect number

* add stream based method. refactor UT

* refactor UT using bdd style

* removes public modifier

* add jmh benchmark

* use properties and remove uncessary configuration

---------

Co-authored-by: alexyang <alexyang0623@gmail.com>
Co-authored-by: travel2china <163321917+travel2china@users.noreply.github.com>
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alexyang 2024-04-05 22:17:28 +08:00 committed by GitHub
parent ee63f1c19d
commit 7edeb43ed1
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18
algorithms-modules/algorithms-miscellaneous-7/pom.xml
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@ -13,4 +13,22 @@
<version>1.0.0-SNAPSHOT</version>
</parent>
<properties>
<jmh.version>1.35</jmh.version>
</properties>
<dependencies>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-core</artifactId>
<version>${jmh.version}</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-annprocess</artifactId>
<version>${jmh.version}</version>
</dependency>
</dependencies>
</project>

50
algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/perfectnumber/PerfectNumber.java Normal file
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@ -0,0 +1,50 @@
package com.baeldung.algorithms.perfectnumber;
import java.util.stream.IntStream;
class PerfectNumber {
public static boolean isPerfectBruteForce(int number) {
int sum = 0;
for (int i = 1; i <= number / 2; i++) {
if (number % i == 0) {
sum += i;
}
}
return sum == number;
}
public static boolean isPerfectStream(int number) {
int sum = IntStream.rangeClosed(2, (int) Math.sqrt(number))
.filter(test -> number % test == 0)
.reduce(1, (s, test) -> s + test + (number / test));
return sum == number;
}
public static boolean isPerfectEuclidEuler(int number) {
int p = 2;
int perfectNumber = (int) (Math.pow(2, p - 1) * (Math.pow(2, p) - 1));
while (perfectNumber <= number) {
if (perfectNumber == number) {
return true;
}
p++;
perfectNumber = (int) (Math.pow(2, p - 1) * (Math.pow(2, p) - 1));
}
return false;
}
public static boolean isPerfectEuclidEulerUsingShift(int number) {
int p = 2;
int perfectNumber = (2 << (p - 1)) * ((2 << p) - 1);
while (perfectNumber <= number) {
if (perfectNumber == number) {
return true;
}
p++;
perfectNumber = (2 << (p - 1)) * ((2 << p) - 1);
}
return false;
}
}

41
algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/perfectnumber/PerfectNumberBenchmark.java Normal file
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@ -0,0 +1,41 @@
package com.baeldung.algorithms.perfectnumber;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;
@State(Scope.Benchmark)
public class PerfectNumberBenchmark {
@Benchmark
public boolean bruteForceBenchmark() {
return PerfectNumber.isPerfectBruteForce(33550336);
}
@Benchmark
public boolean streamBenchmark() {
return PerfectNumber.isPerfectStream(33550336);
}
@Benchmark
public boolean euclidEulerBenchmark() {
return PerfectNumber.isPerfectEuclidEuler(33550336);
}
@Benchmark
public boolean euclidEulerUsingShiftBenchmark() {
return PerfectNumber.isPerfectEuclidEulerUsingShift(33550336);
}
public static void main(String[] args) throws Exception {
Options options = new OptionsBuilder()
.include(PerfectNumberBenchmark.class.getSimpleName())
.forks(1)
.build();
new Runner(options).run();
}
}

68
algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/perfectnumber/PerfectNumberUnitTest.java Normal file
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@ -0,0 +1,68 @@
package com.baeldung.algorithms.perfectnumber;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;
class PerfectNumberUnitTest {
@Test
void givenPerfectNumber_whenCheckingIsPerfectBruteForce_thenReturnTrue() {
assertTrue(PerfectNumber.isPerfectBruteForce(6));
}
@Test
void givenNonPerfectNumber_whenCheckingIsPerfectBruteForce_thenReturnFalse() {
assertFalse(PerfectNumber.isPerfectBruteForce(10));
}
@Test
void givenNegativeNumber_whenCheckingIsPerfectBruteForce_thenReturnFalse() {
assertFalse(PerfectNumber.isPerfectBruteForce(-28));
}
@Test
void givenPerfectNumber_whenCheckingIsPerfectStream_thenReturnTrue() {
assertTrue(PerfectNumber.isPerfectStream(28));
}
@Test
void givenNonPerfectNumber_whenCheckingIsPerfectStream_thenReturnFalse() {
assertFalse(PerfectNumber.isPerfectStream(10));
}
@Test
void givenNegativeNumber_whenCheckingIsPerfectStream_thenReturnFalse() {
assertFalse(PerfectNumber.isPerfectStream(-6));
}
@Test
void givenPerfectNumber_whenCheckingIsPerfectEuclidEuler_thenReturnTrue() {
assertTrue(PerfectNumber.isPerfectEuclidEuler(28));
}
@Test
void givenNonPerfectNumber_whenCheckingIsPerfectEuclidEuler_thenReturnFalse() {
assertFalse(PerfectNumber.isPerfectEuclidEuler(10));
}
@Test
void givenNegativeNumber_whenCheckingIsPerfectEuclidEuler_thenReturnFalse() {
assertFalse(PerfectNumber.isPerfectEuclidEuler(-6));
}
@Test
void givenPerfectNumber_whenCheckingIsPerfectEuclidEulerUsingShift_thenReturnTrue() {
assertTrue(PerfectNumber.isPerfectEuclidEulerUsingShift(28));
}
@Test
void givenNonPerfectNumber_whenCheckingIsPerfectEuclidEulerUsingShift_thenReturnFalse() {
assertFalse(PerfectNumber.isPerfectEuclidEulerUsingShift(10));
}
@Test
void givenNegativeNumber_whenCheckingIsPerfectEuclidEulerUsingShift_thenReturnFalse() {
assertFalse(PerfectNumber.isPerfectEuclidEulerUsingShift(-6));
}
}