class Iterator(Iterator): """ Enumerates the nodes of a tree. """ def __init__(self, tree): """ (Tree.Iterator, Tree) -> None Constructs an iterator for the given tree. """ super(Tree.Iterator, self).__init__(tree) self._stack = StackAsLinkedList() if not tree.isEmpty: self._stack.push(tree) def next(self): """ (Tree.Iterator) -> Object Returns the next node in the tree. """ if self._stack.isEmpty: raise StopIteration top = self._stack.pop() i = top.degree - 1 while i >= 0: subtree = top.getSubtree(i) if not subtree.isEmpty: self._stack.push(subtree) i -= 1 return top.key
def parsePostfix(input): """ (File) -> ExpresionTree Parses the given file into an expression tree. """ stack = StackAsLinkedList() for line in input.readlines(): for word in line.split(): if word == "+" or word == "-" \ or word == "*" or word == "/": result = ExpressionTree(word) result.attachRight(stack.pop()) result.attachLeft(stack.pop()) stack.push(result) else: stack.push(ExpressionTree(word)) return stack.pop()
class Algorithms(object): def __init__(self): self.stack = StackAsLinkedList() def isBalanced(self, input, output): dic = {"]":"[", "}":"{", ")":"("} for line in input.readlines(): for word in line: if word in dic.values(): self.stack.push(word) result = False elif word in dic.keys(): if self.stack.getTop() == dic[word]: self.stack.pop() result = True else: self.stack.push(word) result = False output.write(str(result) + "\n")
def calculator(input, output): """ (File, File) -> None A very simple reverse-Polish calculator. """ stack = StackAsLinkedList() for line in input.readlines(): for word in line.split(): if word == "+": arg2 = stack.pop() arg1 = stack.pop() stack.push(arg1 + arg2) elif word == "*": arg2 = stack.pop() arg1 = stack.pop() stack.push(arg1 * arg2) elif word == "=": arg = stack.pop() output.write(str(arg) + "\n") else: stack.push(int(word))
def calculator(input, output): """ (File, File) -> None A very simple reverse-Polish calculator. """ stack = StackAsLinkedList() for line in input.readlines(): for word in line.split(): if word == "+": arg2 = stack.pop() arg1 = stack.pop() stack.push(arg1 + arg2) elif word == "*": arg2 = stack.pop() arg1 = stack.pop() stack.push (arg1 * arg2) elif word == "=": arg = stack.pop() output.write(str(arg) + "\n") else: stack.push(int(word))
class Algorithms(object): def __init__(self): self.stack = StackAsLinkedList() def calculator(self, input, output): operators = ["+", "-", "*", "/", "^"] for line in input.readlines(): for word in line.split(): if word in operators: print "it is operator ", word arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push("(%s %s %s)" % (arg1, word, arg2)) elif word == "=": print "it is =" arg = self.stack.pop() output.write(arg + " = " + "\n") print "ans is ", arg else: print "it is number, push it" # make it double self.stack.push(word)
class Algorithms(object): def __init__(self): self.stack = StackAsLinkedList() def calculator(self, input, output): for line in input.readlines(): for word in line.split(): if word == "+": print "it is +" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 + arg2) elif word == "*": print "it is *" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 * arg2) elif word == "-": print "it is -" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 - arg2) elif word == "/": print "it is /" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 / arg2) # exponential expression elif word == "^": print "it is ^" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 ** arg2) elif word == "=": print "it is =" arg = self.stack.pop() output.write(str(arg) + "\n") print "ans is ", arg else: print "it is number" # make it double self.stack.push(float(word)) # remove all by calling purge method of linked list def clear(self): self.stack.purge() # use the iterator of linked list to access every remaining element def printall(self): for ele in self.stack: print ele
class Algorithms(object): def __init__(self): self.stack = StackAsLinkedList() def calculator(self, input, output): for line in input.readlines(): for word in line.split(): if word == "+": print "it is +" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 + arg2) elif word == "*": print "it is *" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 * arg2) elif word == "-": print "it is -" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 - arg2) elif word == "/": print "it is /" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 / arg2) # exponential expression elif word == "^": print "it is ^" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1**arg2) elif word == "=": print "it is =" arg = self.stack.pop() output.write(str(arg) + "\n") print "ans is ", arg else: print "it is number" # make it double self.stack.push(float(word)) # remove all by calling purge method of linked list def clear(self): self.stack.purge() # use the iterator of linked list to access every remaining element def printall(self): for ele in self.stack: print ele
class Algorithms(object): def __init__(self): self.stack = StackAsLinkedList() def calculator(self, input, output): for line in input.readlines(): # prefix is acrtually the reversed version of postfix line = line.split() operation = line[:-1] operation.reverse() operation.append(line[-1]) for word in operation: if word == "+": print "it is +" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 + arg2) elif word == "*": print "it is *" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 * arg2) elif word == "-": print "it is -" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 - arg2) elif word == "/": print "it is /" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 / arg2) # exponential expression elif word == "^": print "it is ^" arg2 = self.stack.pop() arg1 = self.stack.pop() self.stack.push(arg1 ** arg2) elif word == "=": print "it is =" arg = self.stack.pop() output.write(str(arg) + "\n") print "ans is ", arg else: print "it is number" # make it double self.stack.push(float(word)) '''
class Iterator(Iterator): """ Enumerates the objects in an M-way tree. """ def __init__(self, tree): """ (MWayTree.Iterator, MWayTree) -> None Constructs an iterator for the given M-way tree. """ super(MWayTree.Iterator, self).__init__(tree) self._position = 0 self._stack = StackAsLinkedList() def next(self): """ (MWayTree.Iterator) -> Object Returns the next object in this M-way tree. """ if self._stack.isEmpty: if not self._container.isEmpty: self._stack.push(self._container) self._position = 1 else: self._position = self._position + 1 top = self._stack.top if self._position == top.degree: pop = self._stack.pop() i = pop.degree - 1 while i >= 0: subtree = pop.getSubtree(i) if not subtree.isEmpty: self._stack.push(subtree) i = i - 1 self._position = 1 if self._stack.isEmpty: raise StopIteration return self._stack.top.getKey(self._position)
class Algorithms(object): def __init__(self): self.stack = StackAsLinkedList() def calculator(self, input, output): operators = ["+", "-"] priors = ["*", "/"] for line in input.readlines(): flag = 0 size = 0 for word in line.split(): ''' match_left = re.search(r'\(', word) match_right = re.search(r'\)', word) if match_left: self.stack.push(word[1:]) flag = 1 if match_right: self.stack.push(word[:-1]) ''' if word in operators: print "it is an operator: ", word while size >= 3: arg2 = self.stack.pop() op = self.stack.pop() arg1 = self.stack.pop() size -= 3 self.stack.push("%s %s %s" % (arg1, arg2, op)) size += 1 print "push ", arg1, arg2, op self.stack.push(word) print "pushing ", word size += 1 flag = 0 elif word in priors: print "it is a prior: ", word # indicating there are a pair of arg1 * arg2 in stack # waiting for poping out if flag == 1 and size >= 3: arg2 = self.stack.pop() op = self.stack.pop() arg1 = self.stack.pop() size -= 3 self.stack.push("%s %s %s" % (arg1, arg2, op)) size += 1 print "push ", arg1, arg2, op # push the operator itself self.stack.push(word) print "pushing ", word size += 1 flag = 1 elif word == "=": print "it is =" while size >= 3: arg2 = self.stack.pop() op = self.stack.pop() arg1 = self.stack.pop() size -= 3 self.stack.push("%s %s %s" % (arg1, arg2, op)) size += 1 print "push ", arg1, arg2, op output.write("%s %s %s = \n" % (arg1, arg2, op)) print "writing into files", arg1, arg2, op else: print "it is number: ", word self.stack.push(word) print "pushing ", word size += 1