iSharkFly-Docs
/
java-tutorials
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

[sum-intarray-recursion] two recursion approaches to summing int-array (#15385)

This commit is contained in:
Kai Yuan 2023-12-13 04:38:31 +01:00 committed by GitHub
parent 784cb2335c
commit 0323a8168c
3 changed files with 115 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
core-java-modules/core-java-lang-6/pom.xml
View File

@ -23,6 +23,16 @@
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-core</artifactId>
<version>${jmh.version}</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-annprocess</artifactId>
<version>${jmh.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
@ -39,6 +49,11 @@
<artifactId>mapstruct-processor</artifactId>
<version>${mapstruct.version}</version>
</path>
<path>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-annprocess</artifactId>
<version>${jmh.version}</version>
</path>
</annotationProcessorPaths>
</configuration>
</plugin>
@ -50,6 +65,7 @@
<maven.compiler.target>17</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<mapstruct.version>1.6.0.Beta1</mapstruct.version>
<jmh.version>1.37</jmh.version>
</properties>
</project>

38
core-java-modules/core-java-lang-6/src/test/java/com/baeldung/recursivelysumintarray/RecursivelySumIntArrayUnitTest.java Normal file
View File

@ -0,0 +1,38 @@
package com.baeldung.recursivelysumintarray;
import org.junit.jupiter.api.Test;
import java.util.Arrays;
import static org.junit.jupiter.api.Assertions.assertEquals;
public class RecursivelySumIntArrayUnitTest {
private static final int[] INT_ARRAY = { 1, 2, 3, 4, 5 };
static int sumIntArray1(int[] array) {
if (array.length == 1) {
return array[0];
} else {
return array[0] + sumIntArray1(Arrays.copyOfRange(array, 1, array.length));
}
}
static int sumIntArray2(int[] array, int index) {
if (index == 0) {
return array[index];
} else {
return array[index] + sumIntArray2(array, index - 1);
}
}
@Test
void whenUsingSumIntArray1_thenGetExpectedResult() {
assertEquals(15, sumIntArray1(INT_ARRAY));
}
@Test
void whenUsingSumIntArray2_thenGetExpectedResult() {
assertEquals(15, sumIntArray2(INT_ARRAY, INT_ARRAY.length - 1));
}
}

61
core-java-modules/core-java-lang-6/src/test/java/com/baeldung/recursivelysumintarray/SumArrayBenchmark.java Normal file
View File

@ -0,0 +1,61 @@
package com.baeldung.recursivelysumintarray;
import static com.baeldung.recursivelysumintarray.RecursivelySumIntArrayUnitTest.sumIntArray1;
import static com.baeldung.recursivelysumintarray.RecursivelySumIntArrayUnitTest.sumIntArray2;
import java.util.Random;
import java.util.concurrent.TimeUnit;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;
@BenchmarkMode(Mode.AverageTime)
@State(Scope.Thread)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Warmup(iterations = 2)
@Fork(1)
@Measurement(iterations = 5)
public class SumArrayBenchmark {
public static void main(String[] args) throws Exception {
Options options = new OptionsBuilder().include(SumArrayBenchmark.class.getSimpleName())
.build();
new Runner(options).run();
}
@Param({ "10", "10000" })
public int size;
int[] array;
@Setup
public void setup() {
var r = new Random();
array = new int[size];
for (int i = 0; i < size; i++) {
array[i] = r.nextInt();
}
}
@Benchmark
public int withArrayCopy() {
return sumIntArray1(array);
}
@Benchmark
public int withoutArrayCopy() {
return sumIntArray2(array, array.length - 1);
}
}