Implementato alcuni esercizi

esercizi/SQueue.java

@@ -0,0 +1,85 @@
+package esercizi;
+
+import exceptions.EmptyQueueException;
+import queue.Queue;
+import sequence.ArraySequence;
+import stack.ArrayStack;
+
+/**
+ * Created with MONSTER.
+ * User: xgiovio
+ * Date: 13/04/2014
+ * Time: 23:01
+ */
+
+// queue emulated via 2 stacks
+
+public class SQueue<E> implements Queue<E> {
+
+
+    private ArrayStack<E> accoda = new ArrayStack<E>();
+    private ArrayStack<E> decoda = new ArrayStack<E>();
+
+    @Override
+    public void enqueue(E element) {
+
+        accoda.push(element);
+
+    }
+
+    @Override
+    public E dequeue() throws EmptyQueueException {
+
+        if (accoda.isEmpty()){
+            throw new EmptyQueueException();
+        } else {
+
+            E temp;
+            int size = accoda.size();
+            for (int i = 0; i <size; i++) {
+                decoda.push(accoda.pop());
+            }
+            temp = decoda.pop();
+            size = decoda.size();
+            for (int i = 0; i < size; i++) {
+                accoda.push(decoda.pop());
+            }
+            return temp;
+        }
+    }
+
+    @Override
+    public E front() throws EmptyQueueException {
+        if (accoda.isEmpty()){
+            throw new EmptyQueueException();
+        } else {
+
+            E temp;
+            int size = accoda.size();
+            for (int i = 0; i <size; i++) {
+                decoda.push(accoda.pop());
+            }
+            temp = decoda.top();
+            size = decoda.size();
+            for (int i = 0; i < size; i++) {
+                accoda.push(decoda.pop());
+            }
+            return temp;
+        }
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return accoda.isEmpty();
+    }
+
+    @Override
+    public int size() {
+        return accoda.size();
+    }
+
+    @Override
+    public String toString() {
+        return accoda.toString();
+    }
+}