excerise_1_solution

public class Practice_Queue {

	public static void main(String[] args) {
		Queue<Integer> q1 = new Queue<Integer>();
		q1.insert(1);
		q1.insert(7);
		q1.insert(3);
		q1.insert(4);
		q1.insert(0);
		q1.insert(0);
		q1.insert(5);
		q1.insert(5);
		q1.insert(3);
		System.out.println("before:");
		printQueue(q1);
		System.out.println();
		Queue<Integer> q2 = dupi(q1);
		System.out.println("after");
		printQueue(q2);
	}

	/*
	 * input - node-list of integers and a int value
	 * return - the list without the elements containing the value
	 */
	public static Node<Integer> deleteValue(Node<Integer> lst, int val) {
		//if first elements are equal value
		while(lst!=null && lst.getValue()==val) {
			lst = lst.getNext();
		}
		//no occurrence of value
		if(lst==null)
			return null;

		Node<Integer> nd = lst;
		//last element have to delete
		if(nd.getNext() == null) {
			return nd;
		}

		boolean go = true;
		Node<Integer> nxtNd = lst.getNext();
		//search node to delete
		while(nxtNd!=null && go) {
			if( nxtNd.getValue()==val) {
				go =false;
				if(nxtNd.getNext()==null) {
					//last is the one to delete
					nd.setNext(null);
					return lst;
				}
				//node to delete is in middle
				else {
					nxtNd = nxtNd.getNext();
					nd.setNext(nxtNd);
				}
			}
			//not found proceed to next nodes
			else {
				nd = nxtNd;
				nxtNd = nxtNd.getNext();
			}
		}
		return lst;
	}


	/*
	 * input - queue of integers
	 * return  - new queue with numbers appears more than one
	 */
	public static Queue<Integer> dupi(Queue<Integer> oldQ){
		int val = 0;
		Node<Integer> q_List = new Node<Integer>(oldQ.remove());
		Queue<Integer> q =  new Queue<Integer>();
		Node<Integer> nd1 = q_List;
		//copy queue o node-list
		while(!oldQ.isEmpty()) {
			val = oldQ.remove();
			q_List.setNext(new Node<Integer>(val));
			q_List = q_List.getNext();
			q.insert(val);
		}
		boolean init = true;
		//Node<Integer> list;
		Queue<Integer> newQ = new Queue<Integer>();
		while(!q.isEmpty() && q_List!=null) {
			val = q.remove();
			if(val_In_list(nd1, val) > 1) {
				nd1 = deleteValue(nd1, val);
				oldQ.insert(val);
			}
		}
		return oldQ;
	}
	/*
	 * input - queue of integers
	 * output - print queue
	 */
	public static void printQueue(Queue<Integer> q) {
		Queue<Integer> tmp = new Queue<Integer>();
		System.out.print("    ");
		while(!q.isEmpty()) {
			System.out.print(q.head()+"|");
			tmp.insert(q.remove());
		}
		while(!tmp.isEmpty()) {

			q.insert(tmp.remove());
		}
		System.out.println("null");

	}

	//prints the given chain
	public static void printChain(Node<Integer> first){
		while(first.hasNext()) {
			System.out.print(first.getValue() + "->");
			first = first.getNext();
		}
		System.out.print(first.getValue() + "->null\n");

	}

	//how many times value appear in list
	public static int val_In_list(Node<Integer> lst, int value){
		int times = 0;
		while(lst!=null) {
			if(lst.getValue() == value)
				times++;

			lst = lst.getNext();
		}
		return times;
	}
}