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BAEL-5646: String permutation improvements (#12613)

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This commit is contained in:
Eugene Kovko 2022-08-17 22:14:47 +02:00 committed by GitHub
parent fad5f79b8c
commit 2d5e7da1fa
8 changed files with 91 additions and 42 deletions
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10
algorithms-modules/algorithms-miscellaneous-4/src/main/java/com/baeldung/algorithms/stringpermutation/ArrayHelper.java → algorithms-modules/algorithms-miscellaneous-4/src/main/java/com/baeldung/algorithms/stringpermutation/Helper.java
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@ -1,14 +1,20 @@
package com.baeldung.algorithms.stringpermutation;
import java.util.Collection;
import java.util.List;
import java.util.stream.Collectors;
public class ArrayHelper {
public class Helper {
private ArrayHelper() {
private Helper() {
}
static List<Character> toCharacterList(final String string) {
return string.chars().mapToObj(s -> ((char) s)).collect(Collectors.toList());
}
static String toString(Collection<Character> collection) {
return collection.stream().map(Object::toString).collect(Collectors.joining());
}
}

23
algorithms-modules/algorithms-miscellaneous-4/src/main/java/com/baeldung/algorithms/stringpermutation/StringPermutationsApache.java
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@ -1,20 +1,29 @@
package com.baeldung.algorithms.stringpermutation;
import java.util.Collection;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import org.apache.commons.collections4.CollectionUtils;
import org.apache.commons.collections4.iterators.PermutationIterator;
public class StringPermutationsApache {
public Collection<List<Character>> eagerPermutationWithRepetitions(final String string) {
final List<Character> characters = ArrayHelper.toCharacterList(string);
return CollectionUtils.permutations(characters);
public List<String> eagerPermutationWithRepetitions(final String string) {
final List<Character> characters = Helper.toCharacterList(string);
return CollectionUtils.permutations(characters)
.stream()
.map(Helper::toString)
.collect(Collectors.toList());
}
public PermutationIterator<Character> lazyPermutationWithoutRepetitions(final String string) {
final List<Character> characters = ArrayHelper.toCharacterList(string);
return new PermutationIterator<>(characters);
public List<String> lazyPermutationWithoutRepetitions(final String string) {
final List<Character> characters = Helper.toCharacterList(string);
final PermutationIterator<Character> permutationIterator = new PermutationIterator<>(characters);
final List<String> result = new ArrayList<>();
while (permutationIterator.hasNext()) {
result.add(Helper.toString(permutationIterator.next()));
}
return result;
}
}

20
algorithms-modules/algorithms-miscellaneous-4/src/main/java/com/baeldung/algorithms/stringpermutation/StringPermutationsCombinatoricsLib.java
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@ -7,19 +7,21 @@ import org.paukov.combinatorics3.PermutationGenerator.TreatDuplicatesAs;
public class StringPermutationsCombinatoricsLib {
public List<List<Character>> permutationWithoutRepetitions(final String string) {
List<Character> chars = ArrayHelper.toCharacterList(string);
return Generator.permutation(chars)
.simple()
.stream()
.collect(Collectors.toList());
}
public List<String> permutationWithoutRepetitions(final String string) {
List<Character> chars = Helper.toCharacterList(string);
return Generator.permutation(chars)
.simple()
.stream()
.map(Helper::toString)
.collect(Collectors.toList());
}
public List<List<Character>> permutationWithRepetitions(final String string) {
List<Character> chars = ArrayHelper.toCharacterList(string);
public List<String> permutationWithRepetitions(final String string) {
List<Character> chars = Helper.toCharacterList(string);
return Generator.permutation(chars)
.simple(TreatDuplicatesAs.IDENTICAL)
.stream()
.map(Helper::toString)
.collect(Collectors.toList());
}

20
algorithms-modules/algorithms-miscellaneous-4/src/main/java/com/baeldung/algorithms/stringpermutation/StringPermutationsGuava.java
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@ -1,18 +1,22 @@
package com.baeldung.algorithms.stringpermutation;
import com.google.common.collect.Collections2;
import java.util.Collection;
import java.util.List;
import java.util.stream.Collectors;
public class StringPermutationsGuava {
public Collection<List<Character>> permutationWithRepetitions(final String string) {
final List<Character> characters = ArrayHelper.toCharacterList(string);
return Collections2.permutations(characters);
public List<String> permutationWithRepetitions(final String string) {
final List<Character> characters = Helper.toCharacterList(string);
return Collections2.permutations(characters).stream()
.map(Helper::toString)
.collect(Collectors.toList());
}
public List<String> permutationWithoutRepetitions(final String string) {
final List<Character> characters = Helper.toCharacterList(string);
return Collections2.orderedPermutations(characters).stream()
.map(Helper::toString)
.collect(Collectors.toList());
}
public Collection<List<Character>> permutationWithoutRepetitions(final String string) {
final List<Character> characters = ArrayHelper.toCharacterList(string);
return Collections2.orderedPermutations(characters);
}
}

36
algorithms-modules/algorithms-miscellaneous-4/src/test/java/com/baeldung/algorithms/stringpermutation/HelperUnitTest.java Normal file
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@ -0,0 +1,36 @@
package com.baeldung.algorithms.stringpermutation;
import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
import java.util.Arrays;
import java.util.List;
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 HelperUnitTest {
@ParameterizedTest
@MethodSource("stringProvider")
void toListTest(String value, List<Character> expected) {
final List<Character> actual = Helper.toCharacterList(value);
assertThat(expected).isEqualTo(actual);
}
@ParameterizedTest
@MethodSource("stringProvider")
void toStringTest(String expected, List<Character> value) {
final String actual = Helper.toString(value);
assertThat(expected).isEqualTo(actual);
}
static Stream<Arguments> stringProvider() {
return Stream.of(
Arguments.of("hello", Arrays.asList('h', 'e', 'l', 'l', 'o')),
Arguments.of("abc", Arrays.asList('a','b','c')),
Arguments.of("12345", Arrays.asList('1', '2', '3', '4', '5'))
);
}
}

15
algorithms-modules/algorithms-miscellaneous-4/src/test/java/com/baeldung/algorithms/stringpermutation/StringPermutationsApacheUnitTest.java
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@ -2,22 +2,19 @@ package com.baeldung.algorithms.stringpermutation;
import static org.assertj.core.api.Assertions.assertThat;
import java.util.Collection;
import java.util.List;
import org.apache.commons.collections4.iterators.PermutationIterator;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.CsvSource;
class StringPermutationsApacheUnitTest {
@ParameterizedTest
@CsvSource({"abc, 6",
"hello, 120",
"aaaaaa, 720"})
@DisplayName("Apache permutation for ")
void testPermutationsWithRepetitions(String string, int numberOfPermutations) {
StringPermutationsApache permutationGenerator = new StringPermutationsApache();
final Collection<List<Character>> permutations = permutationGenerator.eagerPermutationWithRepetitions(string);
final List<String> permutations = permutationGenerator.eagerPermutationWithRepetitions(string);
final int size = permutations.size();
assertThat(permutations)
.as("\"%s\" should have %d permutation, but had %d", string, numberOfPermutations, size)
@ -30,12 +27,8 @@ class StringPermutationsApacheUnitTest {
"aaaaaa, 720"})
void testPermutationsWithoutRepetitions(String string, int numberOfPermutations) {
StringPermutationsApache permutationGenerator = new StringPermutationsApache();
final PermutationIterator<Character> permutations = permutationGenerator.lazyPermutationWithoutRepetitions(string);
int size = 0;
while (permutations.hasNext()) {
permutations.next();
++size;
}
final List<String> permutations = permutationGenerator.lazyPermutationWithoutRepetitions(string);
int size = permutations.size();
assertThat(size)
.as("\"%s\" should have %d permutation, but had %d", string, numberOfPermutations, size)
.isEqualTo(numberOfPermutations);

4
algorithms-modules/algorithms-miscellaneous-4/src/test/java/com/baeldung/algorithms/stringpermutation/StringPermutationsCombinatoricsLibUnitTest.java
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@ -14,7 +14,7 @@ class StringPermutationsCombinatoricsLibUnitTest {
"aaaaaa, 720"})
void testPermutationsWithRepetitions(String string, int numberOfPermutations) {
StringPermutationsCombinatoricsLib permutationGenerator = new StringPermutationsCombinatoricsLib();
final List<List<Character>> permutations = permutationGenerator.permutationWithRepetitions(string);
final List<String> permutations = permutationGenerator.permutationWithRepetitions(string);
final int size = permutations.size();
assertThat(permutations)
.as("\"%s\" should have %d permutation, but had %d", string, numberOfPermutations, size)
@ -27,7 +27,7 @@ class StringPermutationsCombinatoricsLibUnitTest {
"aaaaaa, 1"})
void testPermutationsWithoutRepetitions(String string, int numberOfPermutations) {
StringPermutationsCombinatoricsLib permutationGenerator = new StringPermutationsCombinatoricsLib();
final List<List<Character>> permutations = permutationGenerator.permutationWithoutRepetitions(string);
final List<String> permutations = permutationGenerator.permutationWithoutRepetitions(string);
final int size = permutations.size();
assertThat(permutations)
.as("\"%s\" should have %d permutation, but had %d", string, numberOfPermutations, size)

5
algorithms-modules/algorithms-miscellaneous-4/src/test/java/com/baeldung/algorithms/stringpermutation/StringPermutationsGuavaUnitTest.java
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@ -2,7 +2,6 @@ package com.baeldung.algorithms.stringpermutation;
import static org.assertj.core.api.Assertions.assertThat;
import java.util.Collection;
import java.util.List;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.CsvSource;
@ -15,7 +14,7 @@ class StringPermutationsGuavaUnitTest {
"aaaaaa, 720"})
void testPermutationsWithRepetitions(String string, int numberOfPermutations) {
StringPermutationsGuava permutationGenerator = new StringPermutationsGuava();
final Collection<List<Character>> permutations = permutationGenerator.permutationWithRepetitions(string);
final List<String> permutations = permutationGenerator.permutationWithRepetitions(string);
final int size = permutations.size();
assertThat(permutations)
.as("\"%s\" should have %d permutation, but had %d", string, numberOfPermutations, size)
@ -28,7 +27,7 @@ class StringPermutationsGuavaUnitTest {
"aaaaaa, 1"})
void testPermutationsWithoutRepetitions(String string, int numberOfPermutations) {
StringPermutationsGuava permutationGenerator = new StringPermutationsGuava();
final Collection<List<Character>> permutations = permutationGenerator.permutationWithoutRepetitions(string);
final List<String> permutations = permutationGenerator.permutationWithoutRepetitions(string);
final int size = permutations.size();
assertThat(permutations)
.as("\"%s\" should have %d permutation, but had %d", string, numberOfPermutations, size)