fix few details, stacks

src/abstract_structures/queues/animal_shelter.py

@@ -1,3 +1,10 @@
+#!/usr/bin/python
+
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+""" A class for an animal shelter"""
+
 class Node(object):
     def __init__(self, name, which):
         self.name = name

src/abstract_structures/queues/linked_queue.py

@@ -19,7 +19,7 @@ class LinkedQueue(object):
 
 
     def isEmpty(self):
-        return bool(self.head)
+        return not bool(self.head)
 
 
     def dequeue(self):

src/abstract_structures/queues/queue.py

@@ -10,7 +10,7 @@ class Queue(object):
         self.items = []
 
     def isEmpty(self):
-        return bool(self.items)
+        return not bool(self.items)
 
     def enqueue(self, item):
         self.items.insert(0, item)

src/abstract_structures/queues/queue_from_two_stacks.py

@@ -54,7 +54,7 @@ class Queue(object):
             return "Queue empty!"
 
     def isEmpty(self):
-        return not (bool(self.in_stack) or bool(self.out_stack))
+        return not ((bool(self.in_stack) or bool(self.out_stack)))
 
 
 

src/abstract_structures/stacks/banlance_parenthesis_str_stack.py

@@ -1,40 +1,42 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+''' use a stack to balance the parenteses of a string '''
+
 
 from stack import Stack
 
-def balance_par_str_with_stack(symbolString):
+def balance_par_str_with_stack(str1):
-    ''' use a stack to balance the parenteses of a string '''
+
     s = Stack()
     balanced = True
     index = 0
-    while index < len(symbolString) and balanced:
+
-        symbol = symbolString[index]
+    while index < len(str1) and balanced:
+
+        symbol = str1[index]
+
         if symbol == "(":
             s.push(symbol)
+
         else:
             if s.isEmpty():
                 balanced = False
             else:
                 s.pop()
+
         index = index + 1
 
     if balanced and s.isEmpty():
         return True
+
     else:
         return False
 
 
 
-
+if __name__ == '__main__':
-def test_balance_par_str_with_stack(module_name='this module'):
     print(balance_par_str_with_stack('((()))'))
     print(balance_par_str_with_stack('(()'))
-        
-    s = 'Tests in {name} have {con}!'
-    print(s.format(name=module_name, con='passed'))
-
-
-if __name__ == '__main__':
-    test_balance_par_str_with_stack()

src/abstract_structures/stacks/dec2bin_with_stack.py

@@ -1,28 +1,30 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+'''transform a decimal number to a binary number with a stack '''
+
 
 from stack import Stack
 
 def dec2bin_with_stack(decnum):
-    '''transform a decimal number to a binary number with a stack '''
+
     s = Stack()
     str_aux = ''
+
     while decnum > 0:
         dig = decnum % 2
         decnum = decnum//2
         s.push(dig)
+
     while not s.isEmpty():
         str_aux += str(s.pop())
+
     return str_aux
 
 
-def test_dec2bin_with_stack(module_name='this module'):
-    decnum = 9
-    assert(dec2bin_with_stack(decnum) == '1001')
-    s = 'Tests in {name} have {con}!'
-    print(s.format(name=module_name, con='passed'))
-
 
 if __name__ == '__main__':
-    test_dec2bin_with_stack()
+    decnum = 9
+    assert(dec2bin_with_stack(decnum) == '1001')

src/abstract_structures/stacks/linked_stack.py

@@ -1,52 +1,73 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
-# steinkirch at gmail
 
-class Node:
+__author__ = "Mari Wahl"
-    def __init__(self, value=None):
+__email__ = "marina.w4hl@gmail.com"
+
+
+""" A stack made of linked list"""
+
+
+
+class Node(object):
+    def __init__(self, value=None, pointer=None):
         self.value = value
-        self.next = None
+        self.pointer = pointer
 
-class StackwithNodes:
+
-    ''' Define a Stack with nodes'''
+class Stack(object):
     def __init__(self):
-        self.top = None
+        self.head = None
 
     def isEmpty(self):
-        return bool(self.top)
+        return not bool(self.head)
+
+    def push(self, item):
+        self.head = Node(item, self.head)
+
 
     def pop(self):
-        node = self.top
+        if self.head:
-        self.top = node.next
+            node = self.head
+            self.head = node.pointer
             return node.value
+        else:
+            print('Stack is empty.')
 
-    def push(self, value):
-        node = Node(value)
-        node.next = self.top
-        self.top = node
-
-    def size(self):
-        node = self.top
-        if node not None: num_nodes = 1
-        else: return 0
-        while node.next:
-            num_nodes += 1
-            node = node.next
-        return num_nodes
 
     def peek(self):
-        return self.top.value
+        if self.head:
+            return self.head.value
+        else:
+            print('Stack is empty.')
+
+
+    def size(self):
+        node = self.head
+        count = 0
+        while node:
+            count +=1
+            node = node.pointer
+        return count
+
+
+    def _printList(self):
+        node = self.head
+        while node:
+            print(node.value)
+            node = node.pointer
 
 
-def main():
-    stack = StackwithNodes()
-    stack.push(1)
-    stack.push(2)
-    stack.push(3)
-    print(stack.size())    
-    print(stack.peek())   
-    print(stack.pop())  
-    print(stack.peek())    
 
 if __name__ == '__main__':
-    main()
+    stack = Stack()
+    print("Is the stack empty? ", stack.isEmpty())
+    print("Adding 0 to 10 in the stack...")
+    for i in range(10):
+        stack.push(i)
+    stack._printList()
+    print("Stack size: ", stack.size())
+    print("Stack peek : ", stack.peek())
+    print("Pop...", stack.pop())
+    print("Stack peek: ", stack.peek())
+    print("Is the stack empty? ", stack.isEmpty())
+    stack._printList()

src/abstract_structures/stacks/reverse_string_with_stack.py

@@ -1,30 +1,31 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
-# steinkirch at gmail
 
-import sys
+__author__ = "Mari Wahl"
-import stack
+__email__ = "marina.w4hl@gmail.com"
+
+''' Uses a stack to reverse a string '''
+
+from stack import Stack
 
 def reverse_string_with_stack(str1):
-  ''' Uses a stack to reverse a string '''
+
-  s = stack.Stack()
+  s = Stack()
   revStr = ''
+
   for c in str1:
     s.push(c)
+
   while not s.isEmpty():
     revStr += s.pop()
+
   return revStr
 
 
-def test_reverse_string_with_stack():
-    str1 = 'Buffy is a Slayer!'
-    assert(reverse_string_with_stack(str1) == '!reyalS a si yffuB')
-    print('Tests passed!')
-
 
 if __name__ == '__main__':
-    test_reverse_string_with_stack()   
+  str1 = 'Buffy is a Slayer!'
-
+  print(str1)
+  print(reverse_string_with_stack(str1))
 
 
 

src/abstract_structures/stacks/set_of_stacks.py

@@ -1,47 +1,57 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
-# steinkirch at gmail
 
-class SetOfStacks(list):
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+""" define a class for a set of stacks """
+
+from stack import Stack
+
+class SetOfStacks(Stack):
     def __init__(self, capacity=4):
-        self.stacks = []
+        self.setofstacks = []
-        self.last_stack = []
+        self.items = []
         self.capacity = capacity
-        self.stacks.append(self.last_stack)
 
-    def __repr__(self):
-        return str(self.stacks)
 
     def push(self, value):
-        last_stack = self.last_stack
+        if self.size() >= self.capacity:
-        if len(last_stack) is self.capacity:
+            self.setofstacks.append(self.items)
-            last_stack = []
+            self.items = []
-            self.last_stack = last_stack
+        self.items.append(value)
-            self.stacks.append(last_stack)
+
-        last_stack.append(value)
 
     def pop(self):
-        last_stack = self.last_stack
+        value = self.items.pop()
-        value = last_stack.pop()
+        if self.isEmpty() and self.setofstacks:
-        if len(last_stack) is 0:
+            self.items = self.setofstacks.pop()
-            self.stacks.pop()
-            self.last_stack = self.stacks[-1]
         return value
 
 
-def main():
+    def sizeStack(self):
-    stack = SetOfStacks()
+        return len(self.setofstacks)*self.capacity + self.size()
-    stack.push(1)
+
-    stack.push(2)
+
-    stack.push(3)
+    def __repr__(self):
-    stack.push(4)
+        aux = []
-    stack.push(5)
+        for s in self.setofstacks:
-    stack.push(6)
+             aux.extend(s)
-    print(stack)
+        aux.extend(self.items)
-    stack.pop()
+        return '{}'.format(aux)
-    stack.pop()
+
-    stack.pop()
+
-    print(stack)
 
 if __name__ == '__main__':
-    main()
+    capacity = 5
+    stack = SetOfStacks(capacity)
+    print("Is the stack empty? ", stack.isEmpty())
+    print("Adding 0 to 10 in the stack...")
+    for i in range(10):
+        stack.push(i)
+    print(stack)
+    print("Stack size: ", stack.sizeStack())
+    print("Stack peek : ", stack.peek())
+    print("Pop...", stack.pop())
+    print("Stack peek: ", stack.peek())
+    print("Is the stack empty? ", stack.isEmpty())
+    print(stack)

src/abstract_structures/stacks/setofStacks.py

@@ -1,165 +0,0 @@
-from stack import Stack, Node
-
-class SetOfStacks(object):
-    def __init__(self, capacity):
-        assert(capacity > 1)
-        self.capacity = capacity        
-        self.stack_now = None
-        self.stack_now_size = 0               
-        self.old_stacks = []
-                    
-                    
-    def _checkIfFull(self):
-        return self.stack_now_size == self.capacity
-        
-
-    def _addStack(self):       
-        self.stack_now =  Stack()
-        self.stack_now_size = 0
-        
-                        
-    def _archiveStack(self):
-        self.old_stacks.append(self.stack_now)
-        self.stack_now = None
-        self.stack_now_size = 0   
-
-     
-    def _popItem(self):
-        if self.stack_now.top:
-            value = self.stack_now.top.value
-            if self.stack_now.top.next:
-                node = self.stack_now.top
-                self.stack_now.top = self.stack_now.top.next              
-            else:
-                self.stack_now = [] 
-            return value
-        raise Exception('Stack is empty.')    
-    
-
-    def numberOfStacksUsed(self):
-        if self.stack_now:
-            return len(self.old_stacks) + 1
-        else:
-            return len(self.old_stacks) 
-
-
-    def seeTop(self):
-        if self.stack_now:
-            return self.stack_now.top.value
-        elif self.old_stacks:
-            return self.old_stacks[-1].top.value
-        raise Exception('Stack is Empty')
-       
-            
-    def isEmpty(self):
-        return not (bool(self.stack_now) or bool(self.old_stacks))
-           
-    
-    def _sizeStackInUse(self):
-        return self.stack_now_size
-
-
-    def size(self):
-        return self._sizeStackInUse() + self.capacity*len(self.old_stacks)
-                        
- 
-    def push(self, item):
-        if not self.stack_now:
-             self._addStack()
-        
-        node = Node(item)
-        node.next = self.stack_now.top
-        self.stack_now.top = node         
-        
-        self.stack_now_size += 1
-        
-        if self._checkIfFull():
-            self._archiveStack()
-        
-        
-    def pop(self):  
-        if not self.stack_now:
-            if not self.old_stacks:
-                raise Exception('Stack is empty')
-            else:
-                self.stack_now = self.old_stacks.pop()
-                self.stack_now_size = self.capacity - 1
-                self._popItem()
-        else:
-            self._popItem() 
-            if self.stack_now:
-                self.stack_now_size -= 1
-            else:
-                self.stack_now_size = 0
-            
-
-        
-def main():
-    s1 = SetOfStacks(3)
-    
-    print(s1.numberOfStacksUsed())
-    print(s1.isEmpty())
-    print(s1.size())
-    
-    s1.push(1)
-    print('Push item 1')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())
-    
-    s1.push(2)
-    s1.push(3)
-    print('Push item 2 and 3')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())
-    
-    s1.push(4)
-    print('Push item 4')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())   
-    
-    s1.push(5)
-    print('Push item 5')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())  
-    
-    s1.pop()
-    print('Pop item 5')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())  
-    
-    s1.pop()
-    print('Pop item 4')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())  
-    
-    s1.pop()
-    s1.pop()
-    print('Pop item 3 e 2')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())  
-    
-    s1.pop()
-    print('Pop item 1')
-    print(s1.numberOfStacksUsed())
-    print(s1.isEmpty())
-    print(s1.size())  
-    
-    
-    
-   
-if __name__ == '__main__':
-    main()           

src/abstract_structures/stacks/setofStacksList.py

@@ -1,154 +0,0 @@
-from stack import StackList
-
-class SetOfStacksList(object):
-    def __init__(self, capacity):
-        assert(capacity > 1)
-        self.capacity = capacity        
-        self.stack_now = []            
-        self.old_stacks = []                   
-                    
-    def _checkIfFull(self):
-        return len(self.stack_now) == self.capacity
-              
-                        
-    def _archiveStack(self):
-        self.old_stacks.append(self.stack_now)
-        self.stack_now = []
-
-
-    def _popItem(self):
-        if self.stack_now:
-            return self.stack_now.pop()
-        raise Exception('Stack is empty.')    
- 
- 
-    def _sizeStackInUse(self):
-        return len(self.stack_now)  
-
-
-    def numberOfStacksUsed(self):
-        if self.stack_now:
-            return len(self.old_stacks) + 1
-        else:
-            return len(self.old_stacks) 
-
-
-    def seeTop(self):
-        if self.stack_now:
-            return self.stack_now[-1]
-        elif self.old_stacks:
-            return self.old_stacks[-1][-1]
-        raise Exception('Stack is Empty')
-       
-            
-    def isEmpty(self):
-        return not(bool(self.stack_now) or bool(self.old_stacks))
-           
-           
-    def size(self):
-        return len(self.stack_now) + self.capacity*len(self.old_stacks)
-                        
-                        
-    def push(self, item):
-        self.stack_now.append(item)         
-        if self._checkIfFull():
-            self._archiveStack()
-        
-        
-    def pop(self):  
-        if not self.stack_now:
-            if not self.old_stacks:
-                raise Exception('Stack is empty')
-            else:
-                self.stack_now = self.old_stacks.pop()
-        return self.stack_now.pop()
-        
-    def popAt(self, index):
-        number_of_stacks = self.size()
-        if index < number_of_stacks:
-            if index == number_of_stacks - 1 and  self.stack_now:
-                return self.stack_now.pop()
-            if index < number_of_stacks - 1:
-                stack_here = self.old_stacks[index]
-                return stack_here.pop()
-            raise Exception('Stack at index {} is empty.'.format(index))
-        raise Exception('Index larger than the number of stacks.')
-            
-    def printStacks(self):
-        return str(self.old_stacks), str(self.stack_now)
-
-        
-def main():
-    s1 = SetOfStacksList(3)
-    
-    print(s1.numberOfStacksUsed())
-    print(s1.isEmpty())
-    print(s1.size())
-    
-    s1.push(1)
-    print('Push item 1')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())
-    
-    s1.push(2)
-    s1.push(3)
-    print('Push item 2 and 3')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())
-    
-    s1.push(4)
-    print('Push item 4')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())   
-    
-    s1.push(5)
-    print('Push item 5')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())  
-    
-    s1.pop()
-    print('Pop item 5')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())  
-    
-    s1.pop()
-    print('Pop item 4')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())  
-    
-    s1.pop()
-    s1.pop()
-    print('Pop item 3 e 2')
-    print(s1.numberOfStacksUsed())
-    print(s1.seeTop())
-    print(s1.isEmpty())
-    print(s1.size())  
-    
-    s1.pop()
-    print('Pop item 1')
-    print(s1.numberOfStacksUsed())
-    print(s1.isEmpty())
-    print(s1.size())  
-    
-    
-    s2 = SetOfStacksList(3)
-    for i in range(1, 11):
-        s2.push(i)
-    print(s2.printStacks())
-    print(s2.popAt(2))
-    
-   
-if __name__ == '__main__':
-    main()           

src/abstract_structures/stacks/sort_stack.py

@@ -1,21 +0,0 @@
-def sortStack(s):
-    bufs = []
-    while s:
-        item = s.pop()
-        count, i = 0, 0
-        while bufs and bufs[-1] > item:
-            s.append(bufs.pop())
-            count += 1
-        bufs.append(item)  
-        while i < count:
-            bufs.append(s.pop())
-            i += 1
-    return bufs
-
-def main():
-    s = [3, 5, 1, 2, 6, 7, 8]
-    print(sortStack(s))
-
-    
-if __name__ == '__main__':
-    main()

src/abstract_structures/stacks/stack.py

@@ -1,40 +1,53 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
+''' define the stack class '''
+
 
 class Stack(object):
-    ''' define the stack class '''
     def __init__(self):
         self.items = []
 
     def isEmpty(self):
-        return self.items == []
+        return not bool(self.items)
 
-    def push(self, items):
+    def push(self, value):
-        self.items.append(items)
+        self.items.append(value)
 
     def pop(self):
-        return self.items.pop()
+        value = self.items.pop()
-        
+        if value:
-    def peek(self):
+            return value
-        return self.items[-1]
+        else:
+            print("Stack is empty.")
 
     def size(self):
         return len(self.items)
 
+    def peek(self):
+        if self.items:
+            return self.items[-1]
+        else:
+            print('Stack is empty.')
+
+    def __repr__(self):
+        return '{}'.format(self.items)
 
 
 
-def main():
-    stack = Stack()
-    stack.push(1)
-    stack.push(2)
-    stack.push(3)
-    print(stack.size())    
-    print(stack.peek())   
-    print(stack.pop())  
-    print(stack.peek())    
-
 
 if __name__ == '__main__':
-    main()
+    stack = Stack()
+    print("Is the stack empty? ", stack.isEmpty())
+    print("Adding 0 to 10 in the stack...")
+    for i in range(10):
+        stack.push(i)
+    print("Stack size: ", stack.size())
+    print("Stack peek : ", stack.peek())
+    print("Pop...", stack.pop())
+    print("Stack peek: ", stack.peek())
+    print("Is the stack empty? ", stack.isEmpty())
+    print(stack)

src/abstract_structures/stacks/stackMinElemO1.py

@@ -1,107 +0,0 @@
-from stack import Stack, Node, StackList
-
-
-class StackMinElen(Stack):
-    def __init__(self):
-        self.top = None
-        self.mins = []
-              
-    def printMin(self):
-        if self.mins:
-            return self.mins[-1]
-        raise Exception('Stack is empty.')
-
-
-    def pop(self):
-        if self.top:
-            self.mins.pop()
-            node = self.top
-            self.top = node.next      
-            return node.value    
-        raise Exception('Stack is empty.')
-
-    
-    def push(self, item): 
-        if self.top:
-            min_so_far = self.mins[-1]
-            if min_so_far > item:
-                self.mins.append(item)
-            else:
-                self.mins.append(min_so_far)
-        else:
-            self.mins.append(item)       
-        node = Node(item)
-        node.next = self.top
-        self.top = node
-        
-        
-        
-
-class StackListMinElen(StackList):
-    def __init__(self):
-        self.items = []
-        self.mins = []
-
-    def printMin(self):
-        if self.mins:
-            return self.mins[-1]
-        raise Exception('Stack is Empty')
-
-    def push(self, item):     
-        self.items.append(item)  
-        if self.mins:
-            if self.mins[-1] > item:
-                self.mins.append(item)
-            else:
-                self.mins.append(self.mins[-1])
-        else:
-            self.mins.append(item)
-                                                          
-    def pop(self):
-        if self.items:
-            self.mins.pop()
-            return self.items.pop()
-        raise Exception('Stack is Empty')
-
-
-
-
-        
-def main():
-    s1 = StackListMinElen()
-    l1 = [4, 2, 6, 3, 1, 5]
-    for i in l1:
-        s1.push(i)  
-    print('Min: ', s1.printMin())
-    print('Pop: ', s1.pop())
-    print('Min: ', s1.printMin())
-    print('Pop: ', s1.pop())
-    print('Min: ', s1.printMin())
-    print('Pop: ', s1.pop())        
-    print('Min: ', s1.printMin())
-    print('Pop: ', s1.pop())        
-    print('Min: ', s1.printMin())
-    print('Pop: ', s1.pop())        
-    print('Min: ', s1.printMin())   
-
-
-    s2 = StackMinElen()
-    l1 = [4, 2, 6, 3, 1, 5]
-    for i in l1:
-        s2.push(i)  
-    print('Min: ', s2.printMin())
-    print('Pop: ', s2.pop())
-    print('Min: ', s2.printMin())
-    print('Pop: ', s2.pop())
-    print('Min: ', s2.printMin())
-    print('Pop: ', s2.pop())        
-    print('Min: ', s2.printMin())
-    print('Pop: ', s2.pop())        
-    print('Min: ', s2.printMin())
-    print('Pop: ', s2.pop())        
-    print('Min: ', s2.printMin())   
-
-
-
-if __name__ == '__main__':
-    main()           

src/abstract_structures/stacks/stack_.py

@@ -1,94 +0,0 @@
-#!/usr/bin/python3
-# steinkirch at gmail.com
-# astro.sunysb.edu/steinkirch
-
-class Node(object):
-    def __init__(self, value=None):
-        self.value = value
-        self.next = None
-
-
-class Stack(object):
-    def __init__(self):
-        self.top = None
-
-    def push(self, item):
-        node = Node(item)
-        node.next = self.top
-        self.top = node
-
-    def pop(self):
-        if self.top:
-            node = self.top
-            self.top = node.next            
-            return node.value
-        raise Exception('Stack is empty.')
-
-    def isEmpty(self):
-        return bool(self.top)
-    
-    def seeTop(self):
-        if self.top:
-            return self.top.value
-        raise Exception('Stack is empty.')
-    
-    def size(self):
-        node = self.top
-        count = 0
-        while node:
-            count +=1
-            node = node.next
-        return count
-   
-            
-class StackList(list):
-    def __init__(self):
-        self.items = []
-     
-    def push(self, item):
-        self.items.append(item)
-        
-    def pop(self):
-        if self.items:
-            return self.items.pop()
-        raise Exception('Stack is empty.')
-       
-    def seeTop(self):
-        if self.items:
-            return self.items[-1]
-        raise Exception('Stack is empty.')
-     
-    def size(self):
-        return len(self.items)
-        
-    def isEmpty(self):
-        return bool(self.items)
-   
-        
-def main():
-    s1 = StackList()
-    print(s1.isEmpty())
-    for i in range(1, 10):
-        s1.push(i)
-    print(s1.isEmpty())
-    print(s1.size())
-    print(s1.seeTop())
-    s1.pop()
-    print(s1.size())
-    print(s1.seeTop())       
-    
-    
-    s2 = Stack()
-    print(s2.isEmpty())
-    for i in range(1, 10):
-        s2.push(i)
-    print(s2.isEmpty())
-    print(s2.size())
-    print(s2.seeTop())
-    s2.pop()
-    print(s2.size())
-    print(s2.seeTop())    
-
-
-if __name__ == '__main__':
-    main()           

src/abstract_structures/stacks/stack_with_min.py

@@ -1,55 +1,78 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
-# steinkirch at gmail
 
-class Stack(list):
+__author__ = "Mari Wahl"
-    def push(self, value):
+__email__ = "marina.w4hl@gmail.com"
-        if len(self) > 0:
-            last = self[-1]
-            minimum = self._find_minimum(value, last)
-        else:
-            minimum = value
-        self.minimum = minimum
-        self.append(NodeWithMin(value, minimum))
 
-    def _find_minimum(self, value, last_value):
+''' A stack with a minimum lookup '''
-        if value < last_value.minimum:
-           return value
-        return last_value.minimum
 
-    def min(self):
+from stack import Stack
-        return self.minimum
 
 
 class NodeWithMin(object):
-    def __init__(self, value, minimum):
+    def __init__(self, value=None, minimum=None):
         self.value = value
         self.minimum = minimum
 
+
+class StackMin(Stack):
+    def __init__(self):
+        self.items = []
+        self.minimum = None
+
+
+    def push(self, value):
+        if self.isEmpty() or self.minimum > value:
+           self.minimum = value
+        self.items.append(NodeWithMin(value, self.minimum))
+
+
+    def peek(self):
+        return self.items[-1].value
+
+
+    def peekMinimum(self):
+        return self.items[-1].minimum
+
+
+    def pop(self):
+        item = self.items.pop()
+        if item:
+            if item.value == self.minimum:
+                self.minimum = self.peekMinimum()
+            return item.value
+        else:
+            print("Stack is empty.")
+
     def __repr__(self):
-        return str(self.value)
+        aux = []
+        for i in self.items:
+            aux.append(i.value)
+        return '{}'.format(aux)
 
-    def min(self):
-        return self.minimum
-
-
-
-def main():
-    stack = Stack()
-    stack.push(1)
-    stack.push(2)
-    stack.push(3)
-    node = stack.pop()
-    print(node.minimum)
-    stack.push(0)
-    stack.push(4)
-    node = stack.pop()
-    print(node.min())
-    print(stack.min())
-    print(stack)
 
 
 if __name__ == '__main__':
-    main()   
+    stack = StackMin()
+    print("Is the stack empty? ", stack.isEmpty())
+    print("Adding 0 to 10 in the stack...")
+    for i in range(10,3, -1):
+        stack.push(i)
+    print(stack)
 
+    print("Stack size: ", stack.size())
+    print("Stack peek and peekMinimum : ", stack.peek(), stack.peekMinimum())
+    print("Pop...", stack.pop())
+    print("Stack peek and peekMinimum : ", stack.peek(), stack.peekMinimum())
+    print("Is the stack empty? ", stack.isEmpty())
+    print(stack)
 
+    for i in range(5, 1, -1):
+        stack.push(i)
+    print(stack)
+
+    print("Stack size: ", stack.size())
+    print("Stack peek and peekMinimum : ", stack.peek(), stack.peekMinimum())
+    print("Pop...", stack.pop())
+    print("Stack peek and peekMinimum : ", stack.peek(), stack.peekMinimum())
+    print("Is the stack empty? ", stack.isEmpty())
+    print(stack)

src/abstract_structures/stacks/towers_of_hanoi.py

@@ -1,16 +1,28 @@
-from stack import Stack, Node
+#!/usr/bin/python
+
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
+""" Implement the 'towers of hanoi'"""
+
+from linked_stack import Stack, Node
 
 
 def moveTop(s1, s3):
+
     s3.append(s1.pop())
 
+
 def moveDisks(n, s1, s3, s2):
+
     if n < 1: return
     moveDisks(n - 1, s1, s2, s3)
     moveTop(s1, s3)
     moveDisks(n -1, s2, s3, s1)
 
 
+
 def towersOfHanoi(n):
     s1 = [x+1 for x in range(n)]
     s2 = []
@@ -20,7 +32,10 @@ def towersOfHanoi(n):
     moveDisks(n, s1, s3, s2)
 
     print('The first stick is {0} and the third stick has {1}'.format(s1, s3))
+
     return s3
 
+
+
 if __name__ == '__main__':
     towersOfHanoi(6)