Paper: Stacks-Queues Exercise

stacks_queues/queue.py

@@ -11,6 +11,7 @@ class Queue:
 
     def __init__(self):
         self.store = [None] * INITIAL_QUEUE_SIZE
+        #buffer_size is the size of queue
         self.buffer_size = INITIAL_QUEUE_SIZE
         self.front = -1
         self.rear = -1
@@ -23,40 +24,69 @@ def enqueue(self, element):
             In the store are occupied
             returns None
         """
-        pass
+        # if size of queue is equal to buffer_size we raise a value error
+        if self.size == self.buffer_size:
+            raise QueueFullException
+
+        # if queue is empty  
+        if self.front == -1:
+            self.front = 0
+            self.rear = 1
+            self.store[self.front] = element
+            self.size += 1
+            return
+
+        self.store[self.rear] = element
+        self.rear = (self.rear + 1 ) % self.buffer_size
+        self.size += 1
 
     def dequeue(self):
         """ Removes an element from the Queue
             Raises a QueueEmptyException if 
             The Queue is empty.
             returns None
         """
-        pass
+        # if queue is empty
+        if self.size == 0:
+            raise QueueEmptyException
+
+        temp = self.store[self.front]
+        self.front = (self.front + 1) % self.buffer_size
+        self.size -= 1
+
+        return temp
 
     def front(self):
         """ Returns an element from the front
             of the Queue and None if the Queue
             is empty.  Does not remove anything.
         """
-        pass
+        if self.size == 0: 
+            return None
+
+        return self.store[self.front]
 
 
     def size(self):
         """ Returns the number of elements in
             The Queue
         """
-        pass
+        return self.size
 
     def empty(self):
         """ Returns True if the Queue is empty
             And False otherwise.
         """
-        pass
+        if self.size == 0: 
+            return True
+        else: 
+            return False 
+
 
     def __str__(self):
         """ Returns the Queue in String form like:
             [3, 4, 7]
             Starting with the front of the Queue and
             ending with the rear of the Queue.
         """
-        pass
+        return str([self.store[index % self.buffer_size] for index in range(self.front, (self.front + self.size))])

stacks_queues/stack.py

@@ -12,7 +12,7 @@ def push(self, element):
         """ Adds an element to the top of the Stack.
             Returns None
         """
-        pass
+        self.store.add_first(element)
 
     def pop(self):
         """ Removes an element from the top
@@ -21,18 +21,22 @@ def pop(self):
             The Stack is empty.
             returns None
         """
-        pass
+        if self.store.length() == 0: 
+            raise StackEmptyException
+        else:
+            return self.store.remove_first()
 
     def empty(self):
         """ Returns True if the Stack is empty
             And False otherwise
         """
-        pass
+        if self.store.length() == 0: 
+            return True 
 
     def __str__(self):
         """ Returns the Stack in String form like:
             [3, 4, 7]
             Starting with the top of the Stack and
             ending with the bottom of the Stack.
         """
-        pass
+        return str(self.store)