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BAEL-3484: Partitioning and Sorting an Array With Many Repeated Entries (#8369)

This commit is contained in:
Tapan Avasthi 2020-01-10 21:34:18 +05:30 committed by Sam Millington
parent ac4d7757b7
commit e5b4048419
10 changed files with 279 additions and 0 deletions
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4
algorithms-sorting-2/.gitignore vendored Normal file
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/target/
.settings/
.classpath
.project

64
algorithms-sorting-2/pom.xml Normal file
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<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>algorithms-sorting-2</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>algorithms-sorting-2</name>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<dependencies>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-math3</artifactId>
<version>${commons-math3.version}</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>${commons-codec.version}</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>${junit-jupiter-api.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${org.assertj.core.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>${exec-maven-plugin.version}</version>
</plugin>
</plugins>
</pluginManagement>
</build>
<properties>
<commons-math3.version>3.6.1</commons-math3.version>
<org.assertj.core.version>3.9.0</org.assertj.core.version>
<commons-codec.version>1.11</commons-codec.version>
<junit-jupiter-api.version>5.3.1</junit-jupiter-api.version>
</properties>
</project>

66
algorithms-sorting-2/src/main/java/com/baeldung/algorithms/quicksort/BentleyMcIlroyPartioning.java Normal file
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package com.baeldung.algorithms.quicksort;
import static com.baeldung.algorithms.quicksort.SortingUtils.swap;
public class BentleyMcIlroyPartioning {
public static Partition partition(int input[], int begin, int end) {
int left = begin, right = end;
int leftEqualKeysCount = 0, rightEqualKeysCount = 0;
int partitioningValue = input[end];
while (true) {
while (input[left] < partitioningValue)
left++;
while (input[right] > partitioningValue) {
if (right == begin)
break;
right--;
}
if (left == right && input[left] == partitioningValue) {
swap(input, begin + leftEqualKeysCount, left);
leftEqualKeysCount++;
left++;
}
if (left >= right) {
break;
}
swap(input, left, right);
if (input[left] == partitioningValue) {
swap(input, begin + leftEqualKeysCount, left);
leftEqualKeysCount++;
}
if (input[right] == partitioningValue) {
swap(input, right, end - rightEqualKeysCount);
rightEqualKeysCount++;
}
left++; right--;
}
right = left - 1;
for (int k = begin; k < begin + leftEqualKeysCount; k++, right--) {
if (right >= begin + leftEqualKeysCount)
swap(input, k, right);
}
for (int k = end; k > end - rightEqualKeysCount; k--, left++) {
if (left <= end - rightEqualKeysCount)
swap(input, left, k);
}
return new Partition(right + 1, left - 1);
}
public static void quicksort(int input[], int begin, int end) {
if (end <= begin)
return;
Partition middlePartition = partition(input, begin, end);
quicksort(input, begin, middlePartition.getLeft() - 1);
quicksort(input, middlePartition.getRight() + 1, end);
}
}

38
algorithms-sorting-2/src/main/java/com/baeldung/algorithms/quicksort/DutchNationalFlagPartioning.java Normal file
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package com.baeldung.algorithms.quicksort;
import static com.baeldung.algorithms.quicksort.SortingUtils.compare;
import static com.baeldung.algorithms.quicksort.SortingUtils.swap;
public class DutchNationalFlagPartioning {
public static Partition partition(int[] a, int begin, int end) {
int lt = begin, current = begin, gt = end;
int partitioningValue = a[begin];
while (current <= gt) {
int compareCurrent = compare(a[current], partitioningValue);
switch (compareCurrent) {
case -1:
swap(a, current++, lt++);
break;
case 0:
current++;
break;
case 1:
swap(a, current, gt--);
break;
}
}
return new Partition(lt, gt);
}
public static void quicksort(int[] input, int begin, int end) {
if (end <= begin)
return;
Partition middlePartition = partition(input, begin, end);
quicksort(input, begin, middlePartition.getLeft() - 1);
quicksort(input, middlePartition.getRight() + 1, end);
}
}

29
algorithms-sorting-2/src/main/java/com/baeldung/algorithms/quicksort/Partition.java Normal file
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package com.baeldung.algorithms.quicksort;
public class Partition {
private int left;
private int right;
public Partition(int left, int right) {
super();
this.left = left;
this.right = right;
}
public int getLeft() {
return left;
}
public void setLeft(int left) {
this.left = left;
}
public int getRight() {
return right;
}
public void setRight(int right) {
this.right = right;
}
}

32
algorithms-sorting-2/src/main/java/com/baeldung/algorithms/quicksort/SortingUtils.java Normal file
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package com.baeldung.algorithms.quicksort;
public class SortingUtils {
public static void swap(int[] array, int position1, int position2) {
if (position1 != position2) {
int temp = array[position1];
array[position1] = array[position2];
array[position2] = temp;
}
}
public static int compare(int num1, int num2) {
if (num1 > num2)
return 1;
else if (num1 < num2)
return -1;
else
return 0;
}
public static void printArray(int[] array) {
if (array == null) {
return;
}
for (int e : array) {
System.out.print(e + " ");
}
System.out.println();
}
}

13
algorithms-sorting-2/src/main/resources/logback.xml Normal file
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<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
</pattern>
</encoder>
</appender>
<root level="INFO">
<appender-ref ref="STDOUT"/>
</root>
</configuration>

16
algorithms-sorting-2/src/test/java/com/baeldung/algorithms/quicksort/BentleyMcilroyPartitioningUnitTest.java Normal file
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package com.baeldung.algorithms.quicksort;
import org.junit.Assert;
import org.junit.Test;
public class BentleyMcilroyPartitioningUnitTest {
@Test
public void given_IntegerArray_whenSortedWithBentleyMcilroyPartitioning_thenGetSortedArray() {
int[] actual = {3, 2, 2, 2, 3, 7, 7, 3, 2, 2, 7, 3, 3};
int[] expected = {2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 7, 7, 7};
BentleyMcIlroyPartioning.quicksort(actual, 0, actual.length - 1);
Assert.assertArrayEquals(expected, actual);
}
}

15
algorithms-sorting-2/src/test/java/com/baeldung/algorithms/quicksort/DNFThreeWayQuickSortUnitTest.java Normal file
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package com.baeldung.algorithms.quicksort;
import org.junit.Assert;
import org.junit.Test;
public class DNFThreeWayQuickSortUnitTest {
@Test
public void givenIntegerArray_whenSortedWithThreeWayQuickSort_thenGetSortedArray() {
int[] actual = {3, 5, 5, 5, 3, 7, 7, 3, 5, 5, 7, 3, 3};
int[] expected = {3, 3, 3, 3, 3, 5, 5, 5, 5, 5, 7, 7, 7};
DutchNationalFlagPartioning.quicksort(actual, 0, actual.length - 1);
Assert.assertArrayEquals(expected, actual);
}
}

2
pom.xml
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@ -341,6 +341,7 @@
<module>algorithms-miscellaneous-4</module>
<module>algorithms-miscellaneous-5</module>
<module>algorithms-sorting</module>
<module>algorithms-sorting-2</module>
<module>algorithms-searching</module>
<module>animal-sniffer-mvn-plugin</module>
<module>annotations</module>
@ -985,6 +986,7 @@
<module>algorithms-miscellaneous-4</module>
<module>algorithms-miscellaneous-5</module>
<module>algorithms-sorting</module>
<module>algorithms-sorting-2</module>
<module>algorithms-searching</module>
<module>animal-sniffer-mvn-plugin</module>
<module>annotations</module>