Created
June 22, 2019 17:22
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Sample solution to an algorithmic problem (How to invert a single linked list?)
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| public class InvertSingleLinkedList { | |
| public static void main(String[] args) { | |
| SingleLinkedList list = new SingleLinkedList(); | |
| list.add(1); | |
| list.add(2); | |
| list.add(3); | |
| list.add(4); | |
| System.out.println("--- ORIGINAL: ---"); | |
| for (ListElement element : list) { | |
| System.out.println("||" + element.data); | |
| } | |
| invertSingleLinkedList(list); | |
| System.out.println("--- INVERTED: ---"); | |
| for (ListElement element : list) { | |
| System.out.println("||" + element.data); | |
| } | |
| } | |
| static void invertSingleLinkedList(SingleLinkedList list) { | |
| ListElement previousElement = null; | |
| ListElement currentElement = null; | |
| ListElement nextElement = null; | |
| Iterator<ListElement> iterator = list.iterator(); | |
| while (iterator.hasNext()) { | |
| if (previousElement == null) { | |
| previousElement = iterator.next(); | |
| } else if (currentElement == null) { | |
| currentElement = iterator.next(); | |
| previousElement.next = null; | |
| } else { | |
| nextElement = iterator.next(); | |
| currentElement.next = previousElement; | |
| previousElement = currentElement; | |
| currentElement = nextElement; | |
| } | |
| } | |
| if (currentElement != null) { | |
| currentElement.next = previousElement; | |
| list.head = currentElement; | |
| } | |
| } | |
| static class ListElement { | |
| ListElement next; | |
| int data; | |
| } | |
| static class SingleLinkedList implements Iterable<ListElement> { | |
| ListElement head; | |
| void add(int data) { | |
| ListElement element = new ListElement(); | |
| element.data = data; | |
| if (head == null) { | |
| head = element; | |
| } else { | |
| element.next = head; | |
| head = element; | |
| } | |
| } | |
| @Override | |
| public Iterator<ListElement> iterator() { | |
| return new Iterator<>() { | |
| ListElement currentElement = head; | |
| @Override | |
| public boolean hasNext() { | |
| return currentElement != null; | |
| } | |
| @Override | |
| public ListElement next() { | |
| ListElement temp = currentElement; | |
| currentElement = currentElement.next; | |
| return temp; | |
| } | |
| }; | |
| } | |
| } | |
| } |
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