[ADSx] - RemoveMiddlePoints SSL

import java.util.Iterator;
import java.util.NoSuchElementException;

public class RemoveMiddlePoints {

    public static SLL<Point> deleteMiddlePoints(SLL<Point> list) {
        SLLNode<Point> temp = list.getFirst();
        while (temp.succ != null) {
            if ((temp.element.getX()) == (temp.succ.element.getX())) {
                //isti mu se x koordinatite,vertikalna linija
                if (temp.succ.succ != null) {
                    if (temp.succ.succ.element.getX() == temp.element.getX()) {
                        list.delete(temp.succ);
                    } else {
                        temp = temp.succ;
                    }
                } else break;
            } else if ((temp.element.getY()) == (temp.succ.element.getY())) {
                //isti mu se y koordinatite,horizontalna linija
                if (temp.succ.succ != null) {
                    if (temp.succ.succ.element.getY() == temp.element.getY()) {
                        list.delete(temp.succ);
                    } else {
                        temp = temp.succ;
                    }
                } else break;
            }
        }
        return list;
    }

    public static void main(String[] args) {

        SLL<Point> points = new SLL<>();

        points.insertLast(new Point(2, 3));
        points.insertLast(new Point(4, 3));
        points.insertLast(new Point(6, 3));
        points.insertLast(new Point(6, 3));
        points.insertLast(new Point(10, 3));
        points.insertLast(new Point(12, 3));

        System.out.printf("Original: %s\n", points);
        SLL<Point> result = deleteMiddlePoints(points);
        System.out.printf("Result: %s\n", result);
    }

}


/**
 * Given a linked list of line segments, remove middle points
 * Given a linked list of co-ordinates where adjacent points either form a vertical line or a horizontal line.
 * Delete points from the linked list which are in the middle of a horizontal or vertical line.
 * Examples:
 * <p>
 * Input:  (0,10)->(1,10)->(5,10)->(7,10)
 * |
 * (7,5)->(20,5)->(40,5)
 * Output: Linked List should be changed to following
 * (0,10)->(7,10)
 * |
 * (7,5)->(40,5)
 * The given linked list represents a horizontal line from (0,10)
 * to (7, 10) followed by a vertical line from (7, 10) to (7, 5),
 * followed by a horizontal line from (7, 5) to (40, 5).
 * <p>
 * Input:     (2,3)->(4,3)->(6,3)->(10,3)->(12,3)
 * Output: Linked List should be changed to following
 * (2,3)->(12,3)
 * There is only one vertical line, so all middle points are removed.
 */
class SLLNode<E> {
    protected E element;
    protected SLLNode<E> succ;

    public SLLNode(E elem, SLLNode<E> succ) {
        this.element = elem;
        this.succ = succ;
    }

    @Override
    public String toString() {
        return element.toString();
    }
}

class SLL<E> {
    private SLLNode<E> first;

    public SLL() {
        // Construct an empty SLL
        this.first = null;
    }

    public void deleteList() {
        first = null;
    }

    public int length() {
        int ret;
        if (first != null) {
            SLLNode<E> tmp = first;
            ret = 1;
            while (tmp.succ != null) {
                tmp = tmp.succ;
                ret++;
            }
            return ret;
        } else
            return 0;

    }

    @Override
    public String toString() {
        String ret = new String();
        if (first != null) {
            SLLNode<E> tmp = first;
            ret += tmp + "->";
            while (tmp.succ != null) {
                tmp = tmp.succ;
                ret += tmp + "->";
            }
        } else
            ret = "Prazna lista!!!";
        return ret;
    }

    public void insertFirst(E o) {
        SLLNode<E> ins = new SLLNode<E>(o, first);
        first = ins;
    }

    public void insertAfter(E o, SLLNode<E> node) {
        if (node != null) {
            SLLNode<E> ins = new SLLNode<E>(o, node.succ);
            node.succ = ins;
        } else {
            System.out.println("Dadenot jazol e null");
        }
    }

    public void insertBefore(E o, SLLNode<E> before) {

        if (first != null) {
            SLLNode<E> tmp = first;
            if (first == before) {
                this.insertFirst(o);
                return;
            }
            //ako first!=before
            while (tmp.succ != before)
                tmp = tmp.succ;
            if (tmp.succ == before) {
                SLLNode<E> ins = new SLLNode<E>(o, before);
                tmp.succ = ins;
            } else {
                System.out.println("Elementot ne postoi vo listata");
            }
        } else {
            System.out.println("Listata e prazna");
        }
    }

    public void insertLast(E o) {
        if (first != null) {
            SLLNode<E> tmp = first;
            while (tmp.succ != null)
                tmp = tmp.succ;
            SLLNode<E> ins = new SLLNode<E>(o, null);
            tmp.succ = ins;
        } else {
            insertFirst(o);
        }
    }

    public E deleteFirst() {
        if (first != null) {
            SLLNode<E> tmp = first;
            first = first.succ;
            return tmp.element;
        } else {
            System.out.println("Listata e prazna");
            return null;
        }
    }

    public E delete(SLLNode<E> node) {
        if (first != null) {
            SLLNode<E> tmp = first;
            if (first == node) {
                return this.deleteFirst();
            }
            while (tmp.succ != node && tmp.succ.succ != null)
                tmp = tmp.succ;
            if (tmp.succ == node) {
                tmp.succ = tmp.succ.succ;
                return node.element;
            } else {
                System.out.println("Elementot ne postoi vo listata");
                return null;
            }
        } else {
            System.out.println("Listata e prazna");
            return null;
        }

    }

    public SLLNode<E> getFirst() {
        return first;
    }

    public SLLNode<E> find(E o) {
        if (first != null) {
            SLLNode<E> tmp = first;
            while (tmp.element != o && tmp.succ != null)
                tmp = tmp.succ;
            if (tmp.element == o) {
                return tmp;
            } else {
                System.out.println("Elementot ne postoi vo listata");
            }
        } else {
            System.out.println("Listata e prazna");
        }
        return first;
    }

    public Iterator<E> iterator() {
        // Return an iterator that visits all elements of this list, in left-to-right order.
        return new LRIterator<E>();
    }

    // //////////Inner class ////////////

    private class LRIterator<E> implements Iterator<E> {

        private SLLNode<E> place, curr;

        private LRIterator() {
            place = (SLLNode<E>) first;
            curr = null;
        }

        public boolean hasNext() {
            return (place != null);
        }

        public E next() {
            if (place == null)
                throw new NoSuchElementException();
            E nextElem = place.element;
            curr = place;
            place = place.succ;
            return nextElem;
        }

        public void remove() {
            //Not implemented
        }
    }

    public void mirror() {
        if (first != null) {
            //m=nextsucc, p=tmp,q=next
            SLLNode<E> tmp = first;
            SLLNode<E> newsucc = null;
            SLLNode<E> next;

            while (tmp != null) {
                next = tmp.succ;
                tmp.succ = newsucc;
                newsucc = tmp;
                tmp = next;
            }
            first = newsucc;
        }

    }

    public void merge(SLL<E> in) {
        if (first != null) {
            SLLNode<E> tmp = first;
            while (tmp.succ != null)
                tmp = tmp.succ;
            tmp.succ = in.getFirst();
        } else {
            first = in.getFirst();
        }
    }
}

class Point {

    private int koordinata_x;
    private int koordinata_y;

    public Point(int x, int y) {
        koordinata_x = x;
        koordinata_y = y;
    }

    public int getX() {
        return koordinata_x;
    }

    public void setX(int x) {
        koordinata_x = x;
    }

    public int getY() {
        return koordinata_y;
    }

    public void setY(int y) {
        koordinata_y = y;
    }

    @Override
    public String toString() {
        return "[" + koordinata_x + " , " + koordinata_y + "]";
    }
}