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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;
}
}