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 __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 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()
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 __init__(self): self.stack = StackAsLinkedList()
def __init__(self, numOfStack):
self.stacks = [StackAsLinkedList() for i in range(numOfStack)]
