def iter_visit_first(self,fn):
stack = Stack()
stack.push(self)
while stack.top:
s = stack.pop()
fn(s.root.value)
if s.right:
stack.push(s.right)
if s.left:
stack.push(s.left)
def postfixEval(postfixString):
operateStack = Stack()
tokenList = postfixString.split()
for token in tokenList:
if token in '0123456789':
operateStack.push(int(token))
else:
operate2 = operateStack.pop()
operate1 = operateStack.pop()
result = doMath(token, operate1, operate2)
operateStack.push(result)
return operateStack.pop()
def iter_visit_last(self,fn):
stack = Stack()
isLeaf = self.left is None and self.right is None
if not isLeaf:
stack.push(self)
if self.right:
stack.push(self.right)
if self.left:
stack.push(self.left)
while stack.top:
s = stack.pop()
if s is self:
fn(s.root.value)
continue
isLeaf = s.left is None and s.right is None
if not isLeaf:
stack.push(s)
if self.right:
stack.push(s.right)
if self.left:
stack.push(s.left)
else:
fn(s.root.value)
fn(stack.pop().root.value)
fn(stack.pop().root.value)
def iter_visit_middel(self,fn):
stack = Stack()
isLeaf = self.left is None and self.right is None
if not isLeaf:
if self.right:
stack.push(self.right)
stack.push(self)
if self.left:
stack.push(self.left)
while stack.top:
s = stack.pop()
if s is self:
fn(s.root.value)
s = stack.pop()
isLeaf = s.left is None and s.right is None
if not isLeaf:
if s.right:
stack.push(s.right)
stack.push(s)
if s.left:
stack.push(s.left)
else:
fn(s.root.value)
if stack.top:
fn(stack.pop().root.value)
def treeParser(parsedExpress):
"""
:rtype: object
"""
stack = Stack()
for item in parsedExpress:
if item == '(':
stack.push(item)
elif item == ')':
st = stack.pop()
if stack.pop() != '(':
raise Exception('Bracket not compatible ')
stack.push(st)
elif item in '&|':
tree = Tree(item)
st = stack.pop()
if st == '(':
raise Exception('Binary operator not compatible')
tree.add_left(st)
stack.push(tree)
elif item == '!':
stack.push(Tree(item))
else:
st = stack.pop()
if st == '(':
stack.push(st)
stack.push(Tree(item))
else:
st.add_right(Tree(item))
stack.push(st)
tree = stack.pop()
while stack.top:
st = stack.pop()
st.add_right(tree)
if not stack.top:
return(st)
tree = st
def infixToPostfix(infixString):
#运算符优先级
prec = {'*': 3, '/': 3, '+': 2, '-': 2, '(': 1}
#存放操作符
opStack = Stack()
#存放后缀表达式
postfixList = []
#以空白字符分割中缀表达式
tokenList = infixString.split()
for token in tokenList:
if token in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' or token in '0123456789':
postfixList.append(token)
elif token == '(':
opStack.push(token)
elif token == ')':
topToken = opStack.pop()
while topToken != '(':
postfixList.append(topToken)
topToken = opStack.pop()
else:
while not opStack.isEmpty() and prec[
opStack.peek()] >= prec[token]:
postfixList.append(opStack.pop())
opStack.push(token)
while not opStack.isEmpty():
postfixList.append(opStack.pop())
return ' '.join(postfixList)