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Create a new Strand Sort Algorithm #3205

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Merged
merged 7 commits into from
Aug 6, 2022
Merged

Create a new Strand Sort Algorithm #3205

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ea46518
Create a new StrandSort Algorithm
MarcusCody Aug 3, 2022
f26c44d
Create JUnit tests for Strand Sort Algorithm
MarcusCody Aug 3, 2022
c4da1ed
Package updated
MarcusCody Aug 3, 2022
03fc0b5
Merge branch 'TheAlgorithms:master' into patch-2
MarcusCody Aug 3, 2022
eeaf70b
Change access to static using StrandSort
MarcusCody Aug 3, 2022
ca6748f
import updated
MarcusCody Aug 3, 2022
35ce49c
Merge branch 'master' into patch-2
siriak Aug 6, 2022
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42 changes: 42 additions & 0 deletions src/main/java/com/thealgorithms/sorts/StrandSort.java
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package com.thealgorithms.sorts;
import java.util.Iterator;
import java.util.LinkedList;

public class StrandSort{
// note: the input list is destroyed
public static <E extends Comparable<? super E>>
LinkedList<E> strandSort(LinkedList<E> list){
if(list.size() <= 1) return list;

LinkedList<E> result = new LinkedList<E>();
while(list.size() > 0){
LinkedList<E> sorted = new LinkedList<E>();
sorted.add(list.removeFirst()); //same as remove() or remove(0)
for(Iterator<E> it = list.iterator(); it.hasNext(); ){
E elem = it.next();
if(sorted.peekLast().compareTo(elem) <= 0){
sorted.addLast(elem); //same as add(elem) or add(0, elem)
it.remove();
}
}
result = merge(sorted, result);
}
return result;
}

private static <E extends Comparable<? super E>>
LinkedList<E> merge(LinkedList<E> left, LinkedList<E> right){
LinkedList<E> result = new LinkedList<E>();
while(!left.isEmpty() && !right.isEmpty()){
//change the direction of this comparison to change the direction of the sort
if(left.peek().compareTo(right.peek()) <= 0)
result.add(left.remove());
else
result.add(right.remove());
}
result.addAll(left);
result.addAll(right);
return result;
}

}
39 changes: 39 additions & 0 deletions src/test/java/com/thealgorithms/sorts/StrandSortTest.java
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package com.thealgorithms.sorts;

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;

import java.util.Arrays;
import java.util.LinkedList;


class StrandSortTest {
@Test
// valid test case
public void StrandSortNonDuplicateTest() {
int[] expectedArray = { 1, 2, 3, 4, 5 };
LinkedList<Integer> actualList = StrandSort.strandSort(new LinkedList<Integer>(Arrays.asList(3, 1, 2, 4, 5)));
int[] actualArray = new int[actualList.size()];
for (int i = 0; i < actualList.size(); i++) {
actualArray[i] = actualList.get(i);
}
assertArrayEquals(expectedArray, actualArray);

}

@Test
// valid test case
public void StrandSortDuplicateTest() {
int[] expectedArray = { 2, 2, 2, 5, 7 };
LinkedList<Integer> actualList = StrandSort.strandSort(new LinkedList<Integer>(Arrays.asList(7, 2, 2, 2, 5)));
int[] actualArray = new int[actualList.size()];
for (int i = 0; i < actualList.size(); i++) {
actualArray[i] = actualList.get(i);
}
assertArrayEquals(expectedArray, actualArray);

}

}