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refactor(sorting): remove redundant even-only merge sort strategy

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Володин Герман
2026-08-29 21:21:53 +04:00
parent 715b411eea
commit 56652fda71
2 changed files with 0 additions and 237 deletions
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app/src/main/java/ru/project/sorting/EvenOnlyMergeSortStrategy.java
-60
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@@ -1,60 +0,0 @@
package ru.project.sorting;
import ru.project.collection.MyLinkedList;
import ru.project.collection.MyList;
import java.util.Comparator;
import java.util.function.ToIntFunction;
public class EvenOnlyMergeSortStrategy<T> implements SortStrategy<T> {
private final ToIntFunction<T> valueExtractor;
private final SortStrategy<T> mergeSortStrategy;
public EvenOnlyMergeSortStrategy(ToIntFunction<T> valueExtractor) {
this.valueExtractor = valueExtractor;
this.mergeSortStrategy = new MergeSortStrategy<>();
}
@Override
public void sort(MyList<T> list, Comparator<T> comparator) {
if (list == null || list.size() <= 1) {
return;
}
int evenCount = 0;
for (int i = 0; i < list.size(); i++) {
T element = list.get(i);
if (valueExtractor.applyAsInt(element) % 2 == 0) {
evenCount++;
}
}
if (evenCount <= 1) {
return;
}
MyList<T> evenElements = new MyLinkedList<>();
int[] evenIndexes = new int[evenCount];
int evenIndex = 0;
for (int i = 0; i < list.size(); i++) {
T element = list.get(i);
if (valueExtractor.applyAsInt(element) % 2 == 0) {
evenElements.add(element);
evenIndexes[evenIndex] = i;
evenIndex++;
}
}
mergeSortStrategy.sort(evenElements, comparator);
for (int i = 0; i < evenIndexes.length; i++) {
list.set(evenIndexes[i], evenElements.get(i));
}
}
}
app/src/test/java/ru/project/sorting/EvenOnlyMergeSortStrategyTest.java
-177
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@@ -1,177 +0,0 @@
package ru.project.sorting;
import org.junit.jupiter.api.Test;
import ru.project.collection.MyLinkedList;
import ru.project.collection.MyList;
import ru.project.student.Student;
import static org.junit.jupiter.api.Assertions.assertEquals;
class EvenOnlyMergeSortStrategyTest {
@Test
void shouldSortOnlyEvenElements() {
MyList<Integer> list = new MyLinkedList<>();
list.add(7);
list.add(8);
list.add(3);
list.add(2);
list.add(5);
list.add(4);
EvenOnlyMergeSortStrategy<Integer> strategy =
new EvenOnlyMergeSortStrategy<>(value -> value);
strategy.sort(list, Integer::compare);
assertEquals(7, list.get(0));
assertEquals(2, list.get(1));
assertEquals(3, list.get(2));
assertEquals(4, list.get(3));
assertEquals(5, list.get(4));
assertEquals(8, list.get(5));
assertEquals(6, list.size());
}
@Test
void shouldKeepAllOddElementsUnchanged() {
MyList<Integer> list = new MyLinkedList<>();
list.add(7);
list.add(3);
list.add(5);
list.add(1);
EvenOnlyMergeSortStrategy<Integer> strategy =
new EvenOnlyMergeSortStrategy<>(value -> value);
strategy.sort(list, Integer::compare);
assertEquals(7, list.get(0));
assertEquals(3, list.get(1));
assertEquals(5, list.get(2));
assertEquals(1, list.get(3));
}
@Test
void shouldSortAllEvenElements() {
MyList<Integer> list = new MyLinkedList<>();
list.add(8);
list.add(2);
list.add(6);
list.add(4);
EvenOnlyMergeSortStrategy<Integer> strategy =
new EvenOnlyMergeSortStrategy<>(value -> value);
strategy.sort(list, Integer::compare);
assertEquals(2, list.get(0));
assertEquals(4, list.get(1));
assertEquals(6, list.get(2));
assertEquals(8, list.get(3));
}
@Test
void shouldKeepSingleElementUnchanged() {
MyList<Integer> list = new MyLinkedList<>();
list.add(4);
EvenOnlyMergeSortStrategy<Integer> strategy =
new EvenOnlyMergeSortStrategy<>(value -> value);
strategy.sort(list, Integer::compare);
assertEquals(4, list.get(0));
assertEquals(1, list.size());
}
@Test
void shouldHandleEmptyList() {
MyList<Integer> list = new MyLinkedList<>();
EvenOnlyMergeSortStrategy<Integer> strategy =
new EvenOnlyMergeSortStrategy<>(value -> value);
strategy.sort(list, Integer::compare);
assertEquals(0, list.size());
}
@Test
void shouldUseValueExtractorToDetermineEvenElements() {
MyList<Integer> list = new MyLinkedList<>();
list.add(4);
list.add(3);
list.add(2);
list.add(1);
EvenOnlyMergeSortStrategy<Integer> strategy =
new EvenOnlyMergeSortStrategy<>(value -> value + 1);
strategy.sort(list, Integer::compare);
assertEquals(4, list.get(0));
assertEquals(1, list.get(1));
assertEquals(2, list.get(2));
assertEquals(3, list.get(3));
}
@Test
void shouldUseProvidedComparator() {
MyList<Integer> list = new MyLinkedList<>();
list.add(7);
list.add(2);
list.add(3);
list.add(8);
list.add(5);
list.add(4);
EvenOnlyMergeSortStrategy<Integer> strategy =
new EvenOnlyMergeSortStrategy<>(value -> value);
strategy.sort(list, (first, second) -> Integer.compare(second, first));
assertEquals(7, list.get(0));
assertEquals(8, list.get(1));
assertEquals(3, list.get(2));
assertEquals(4, list.get(3));
assertEquals(5, list.get(4));
assertEquals(2, list.get(5));
}
@Test
void shouldUseStudentRecordBookNumberToDetermineEvenElements() {
MyList<Student> students = new MyLinkedList<>();
students.add(new Student("A01", 4.0, 7));
students.add(new Student("A02", 4.0, 8));
students.add(new Student("A03", 4.0, 3));
students.add(new Student("A04", 4.0, 2));
students.add(new Student("A05", 4.0, 5));
students.add(new Student("A06", 4.0, 4));
SortStrategy<Student> strategy = new EvenOnlyMergeSortStrategy<>(
Student::getRecordBookNumber
);
strategy.sort(students, new StudentRecordBookComparator());
assertEquals(7, students.get(0).getRecordBookNumber());
assertEquals(2, students.get(1).getRecordBookNumber());
assertEquals(3, students.get(2).getRecordBookNumber());
assertEquals(4, students.get(3).getRecordBookNumber());
assertEquals(5, students.get(4).getRecordBookNumber());
assertEquals(8, students.get(5).getRecordBookNumber());
assertEquals(6, students.size());
}
}