Ivana - Scissors

stacks_queues/linked_list.py

@@ -43,12 +43,12 @@ def remove_first(self):
         self.head = self.head.next
         if self.head:
             self.head.previous = None
-        
+
         return value
 
 
     def empty(self):
-      return not self.head
+        return not self.head
 
     # method to find if the linked list contains a node with specified value
     # returns true if found, false otherwise
@@ -57,7 +57,7 @@ def empty(self):
     def search(self, value):
         if not self.head:
             return False
-        
+
         if self.head.value == value:
             return True
 
@@ -66,7 +66,7 @@ def search(self, value):
             if current.value == value:
                 return True
             current = current.next
-        
+
         return False
 
 
@@ -77,7 +77,7 @@ def search(self, value):
     def find_max(self):
         if not self.head:
             return None
-        
+
         current = self.head
         max = current.value
 
@@ -102,7 +102,7 @@ def find_min(self):
             if min > current.value:
                 min = current.value
             current = current.next
-        
+
         return min
 
     # method that returns the length of the singly linked list
@@ -111,13 +111,13 @@ def find_min(self):
     def length(self):
         if not self.head:
             return 0
-        
+
         current = self.head
         length = 0
         while current:
             length += 1
             current = current.next
-        
+
         return length
 
     # method that returns the value at a given index in the linked list
@@ -136,7 +136,7 @@ def get_at_index(self, index):
                 return current.value
             count += 1
             current = current.next
-        
+
         return None
 
     # method to print all the values in the linked list
@@ -149,7 +149,7 @@ def visit(self):
         while current:
             values.append(current.value)
             current = current.next
-        
+
         print(", ".join(values))
 
     # method to delete the first node found with specified value
@@ -158,14 +158,14 @@ def visit(self):
     def delete(self, value):
         if not self.head:
             return None
-        
+
         current = self.head
         if current.value == value:
             self.head = current.next
             if self.head:
                 self.head.previous = None
             else:
-                tail = None
+                self.tail = None
             return None
 
         previous = current
@@ -210,7 +210,7 @@ def add_last(self, value):
         if not self.head:
             self.add_first(value)
             return
-    
+
         self.tail.next = new_node
         new_node.previous = self.tail
         self.tail = new_node
@@ -229,7 +229,7 @@ def remove_last(self):
         return value
 
     # method that returns the value of the last node in the linked list
-    # returns nil if the linked list is empty
+    # returns None if the linked list is empty
     # Time Complexity:  O(n) where n is the number of nodes
     # Space Complexity: O(1)
     def get_last(self):

stacks_queues/queue.py

@@ -1,4 +1,3 @@
-
 INITIAL_QUEUE_SIZE = 20
 
 class QueueFullException(Exception):
@@ -12,50 +11,61 @@ class Queue:
     def __init__(self):
         self.store = [None] * INITIAL_QUEUE_SIZE
         self.buffer_size = INITIAL_QUEUE_SIZE
-        self.front = -1
-        self.rear = -1
+        self.front = 0
+        self.rear = 0
         self.size = 0
-
 
     def enqueue(self, element):
         """ Adds an element to the Queue
             Raises a QueueFullException if all elements
             In the store are occupied
             returns None
         """
-        pass
+        if self.size == self.buffer_size:
+            raise QueueFullException("i'm full 🤰")
+        else:
+            self.size += 1
+            self.store[self.rear] = element
+            self.rear = (self.rear + 1) % self.buffer_size
+
 
     def dequeue(self):
         """ Removes and returns an element from the Queue
-            Raises a QueueEmptyException if 
+            Raises a QueueEmptyException if
             The Queue is empty.
         """
-        pass
 
-    def front(self):
+        if self.empty():
+            raise QueueEmptyException("i'm empty")
+        else:
+            temp = self._front()
+            self.size -= 1
+            self.front = (self.front + 1) % self.buffer_size
+            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
-
-
-    def size(self):
-        """ Returns the number of elements in
-            The Queue
-        """
-        pass
+        return self.store[self.front] if not self.empty() else None
 
     def empty(self):
         """ Returns True if the Queue is empty
             And False otherwise.
         """
-        pass
+        return self.size == 0
 
     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
+        f = self.front
+        helper_list = []
+
+        for i in range(self.size):
+            helper_list.append(self.store[(f+i) % self.buffer_size])
+
+        return "["+", ".join(list(map(str, helper_list)))+"]"

stacks_queues/stack.py

@@ -12,7 +12,8 @@ def push(self, element):
         """ Adds an element to the top of the Stack.
             Returns None
         """
-        pass
+
+        return self.store.add_first(element)
 
     def pop(self):
         """ Removes an element from the top
@@ -21,18 +22,23 @@ def pop(self):
             The Stack is empty.
             returns None
         """
-        pass
+        if not self.empty():
+            return self.store.remove_first()
+        else:
+            raise StackEmptyException("error")
+
 
     def empty(self):
         """ Returns True if the Stack is empty
             And False otherwise
         """
-        pass
+        return self.store.empty()
+
 
     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)