def insert_right(self, new_node):
if self.right_child == None:
self.right_child = BinaryTree(new_node)
else:
t = BinaryTree(new_node)
t.right_child = self.right_child
self.right_child = t
def insert_left(self, new_node):
if self.left_child == None:
self.left_child = BinaryTree(new_node)
else:
t = BinaryTree(new_node)
t.left_child = self.left_child
self.left_child = t
def buildParseTree(fpexp):
fplist = fpexp.split() #splitting a string of expression into list
#(type list)
pStack = Stack() #create empty stack
#(type 'instance')
eTree = BinaryTree('') #top root value
#(type 'instance')
pStack.push(eTree) #pushed current root into the stack
print pStack.size()
currentTree = eTree #current position at a time
#(type 'instance')
for i in fplist:
if i == '(':
currentTree.insertLeft('') #inserts an empty node as a leftChild
#print currentTree
pStack.push(currentTree) #pushes current tree into the stack
print 'StackSize: {}, root: {} iteration(push): {} '.format(
pStack.size(), currentTree.getRootVal(), i)
currentTree = currentTree.getLeftChild(
) #sets current position to the leftChild
elif i not in ['+', '-', '*', '/', ')']:
print '-----before root: {} '.format(currentTree.getRootVal())
currentTree.setRootVal(
int(i)
) #we are located at the node so set the root value to the number
#parent = pStack.pop() #???
#print 'StackSize: {}, parent: {} iteration(pop): digits'.format(pStack.size(), parent.getRootVal())
#currentTree = parent #this sets the current position to the parent node
currentTree = pStack.pop()
print 'StackSize: {}, iteration(pop): digits'.format(
pStack.size())
print '-----after root: {} '.format(currentTree.getRootVal())
elif i in ['+', '-', '*', '/']:
currentTree.setRootVal(
i) #set the value to the operator for "currentTree"
currentTree.insertRight('') # descend to the right child
pStack.push(
currentTree
) #push the new tree to the stack (will it push last updated node or the whole tree? Will it souble it?)
print 'StackSize: {}, root: {} iteration(push): {}'.format(
pStack.size(), currentTree.getRootVal(), i)
currentTree = currentTree.getRightChild(
) # this set the current position to the rightChild
elif i == ')':
currentTree = pStack.pop()
print 'StackSize: {}, root: {} iteration(pop)'.format(
pStack.size(), currentTree.getRootVal(), i)
else:
raise ValueError
print 'eTee root: {} '.format(eTree.getRootVal())
return eTree
def postorder_evaluate(tree: BinaryTree):
opers = {
'+': operator.add,
'-': operator.sub,
'*': operator.mul,
'/': operator.truediv
}
if tree:
res1 = postorder_evaluate(tree.getLeftChild())
res2 = postorder_evaluate(tree.getRightChild())
if res1 and res2:
return opers[tree.getRootVal()](res1, res2)
else:
return tree.getRootVal()
def print_exp(tree: BinaryTree):
# 优化后的方法，去掉每个数字的左右括号
sVal = ''
if tree:
str_val = str(tree.getRootVal())
result = print_exp(tree.getLeftChild()) + str_val + print_exp(
tree.getRightChild())
if str_val.isnumeric():
sVal = result
else:
sVal = '(' + result + ')'
return sVal
def __init__(self, rule, globals=globals()):
tokens = rule.split()
pStack = Stack()
self.tree = BinaryTree('')
pStack.push(self.tree)
current_tree = self.tree
is_func_args = False
self.globals = globals
for token in tokens:
# Open bracket.
if token == '(':
if is_func_args:
parent = pStack.pop()
current_tree = parent
current_tree.insertLeft('')
pStack.push(current_tree)
current_tree = current_tree.getLeftChild()
is_func_args = False
# Function name or arguments.
elif token.lower() not in ['and', 'or', ')']:
if not is_func_args:
current_tree.setRootVal((token, []))
is_func_args = True
continue
current_tree.key[1].append(token)
elif token.lower() in ['and', 'or']:
if is_func_args:
parent = pStack.pop()
current_tree = parent
current_tree.setRootVal(token)
current_tree.insertRight('')
pStack.push(current_tree)
current_tree = current_tree.getRightChild()
is_func_args = False
elif token == ')':
if is_func_args:
parent = pStack.pop()
current_tree = parent
current_tree = pStack.pop()
is_func_args = False
else:
raise ValueError
self.tree = current_tree
# If we have only 1 node (Example: "func1 arg1"), then
# the root node is empty. Make it left child which is not empty.
if self.tree.getRightChild() is None and self.tree.getLeftChild(
) is not None:
self.tree = self.tree.getLeftChild()
def buildParseTree(fpexp):
breakList = listAdjust(fpexp)
#fplist = breakList.split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
# Checks if item passed in from 'fpexp' contains integers or mathemateical operators
for i in breakList:
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in ['+', '-', '*', '/', ')']:
currentTree.setRootVal(int(i))
parent = pStack.pop()
currentTree = parent
elif i in ['+', '-', '*', '/']:
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def buildParseTree(fpexp):
# 按空格分开
fplist = fpexp.split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
for i in fplist:
if i == '(':
currentTree.insertLeft('')
# 保持跟踪父对象的简单解决方案是使用栈
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in ['+', '-', '*', '/', ')']:
currentTree.setRootVal(int(i))
parent = pStack.pop()
currentTree = parent
elif i in ['+', '-', '*', '/']:
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def buildParseTree(fpexp):
fplist = fpexp.split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
for i in fplist:
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in [
'+', '-', '*', '/', ')', '&&', '|', '<', '>', '!', '==', '!=',
'<=', '>=', 'is', 'and', 'or'
]:
currentTree.setRootVal(i)
parent = pStack.pop()
currentTree = parent
elif i in [
'+', '-', '*', '/', ')', '&&', '|', '<', '>', '!', '==', '!=',
'<=', '>=', 'is', 'and', 'or'
]:
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def buildParseTree(equation):
"""
input: a exquation expression, with parenthesis regulated
output: a tree with postorder traversal
"""
equationList = equation.split()
pStack = Stack()
eTree = BinaryTree('')
currentTree = eTree
pStack.push(eTree)
for i in equationList:
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in ['+', '-', '*', '/', ')']:
currentTree.setRootVal(int(i))
parent = pStack.pop()
currentTree = parent
elif i in ['+', '-', '*', '/']:
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = pStack.pop()
else:
raise valueError
return eTree
def build_parse_tree(fpexp):
fplist = fpexp.split()
pstack = Stack()
etree = BinaryTree("")
pstack.push(etree)
current_tree = etree
for i in fplist:
if i == '(':
current_tree.insertLeft("")
pstack.push(current_tree)
current_tree = current_tree.getLeftChild()
elif i not in ['+', '-', '*', '/', ')']:
current_tree.setRootVal(int(i))
parent = pstack.pop()
current_tree = parent
elif i in ['+', '-', '*', '/', ')']:
current_tree.setRootVal(i)
current_tree.insertRight("")
pstack.push(current_tree)
current_tree = current_tree.getRightChild()
elif i == ')':
current_tree = pstack.pop()
else:
raise ValueError
return etree
def buildParseTree(fpexp):
fplist = list(fpexp.replace(' ', ''))
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
for i in fplist:
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in '+-*/)':
currentTree.setRootVal(int(i))
parent = pStack.pop()
currentTree = parent
elif i in '+-*/':
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def buildParseTree(fpexp):
fplist = fpexp.split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
for i in fplist:
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i in ['+', '-', '*', '/']:
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = pStack.pop()
elif i not in ['+', '-', '*', '/', ')']:
try:
currentTree.setRootVal(int(i))
parent = pStack.pop()
currentTree = parent
except ValueError:
raise ValueError("token'{}'is not a valid integer".format(i))
return eTree
def p_tree_comparison(p):
'''tree_comparison : tree_expression operator_comparison tree_expression'''
p[0] = BinaryTree('')
p[0].insertLeft(build_tree_expression(p[1]))
p[0].setRootVal(p[2])
p[0].insertRight(build_tree_expression(p[3]))
def buildParseTree(fpexp):
fplist = fpexp.split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
for i in fplist:
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
##extending to add boolean function
elif i not in ['+', '-', '*', '/', ')','>','<','==','!']:
currentTree.setRootVal(int(i))
parent = pStack.pop()
currentTree = parent
#extending to add boolean function
elif i in ['+', '-', '*', '/','>','<','==','!',')']:
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def buildParseTree(fpexp, aviableOperators=["and", "And", "or", "Or", ")"]):
fplist = fpexp.split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
for i in fplist:
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in aviableOperators:
currentTree.setRootVal(int(i))
parent = pStack.pop()
currentTree = parent
elif i in aviableOperators:
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def evaluate(parseTree: BinaryTree):
opers = {
'+': operator.add,
'-': operator.sub,
'*': operator.mul,
'/': operator.truediv
}
leftC = parseTree.getLeftChild()
rightC = parseTree.getRightChild()
if leftC and rightC:
fn = opers[parseTree.getRootVal()]
return fn(evaluate(leftC), evaluate(rightC))
else:
return parseTree.getRootVal()
def parse_tree(str):
str_split = str.split()
node_stack = Stack()
output_tree = BinaryTree('')
node_stack.push(output_tree)
current_root = output_tree
for each_chara in str_split:
if each_chara == '(':
# for ( in the string
current_root.insertLeft('')
node_stack.push(current_root)
# we conduct all the operations on the current node, and the output node
# is just used for store the first node, which is used to output
current_root = current_root.getLeftChild()
elif each_chara not in ['+', '-', '*', '/', ')']:
# a number to be used for calculation
current_root.setRootVal(int(each_chara))
current_parent = node_stack.pop()
current_root = current_parent
elif each_chara in ['+', '-', '*', '/']:
# if a operator
current_root.setRootVal(each_chara)
current_root.insertRight('')
node_stack.push(current_root)
current_root = current_root.getRightChild()
elif each_chara == ")":
current_root = node_stack.pop()
else:
raise ValueError
return output_tree
def buildParseTree(fpexp):
fplist = fpexp.split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
for i in fplist:
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in ['&', '|', '&~', '|~', ')']:
currentTree.setRootVal(i)
parent = pStack.pop()
currentTree = parent
elif i in ['&', '|', '&~', '|~']:
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def buildParseTree(formula):
formulalist = formula.split() #['('，'3'，'+'，'('，'4'，'*'，'5'，')'，')']
rootStack = Stack() #用于跟踪父节点
Tree = BinaryTree('') #创建一个二叉树
rootStack.push(Tree)
currentTree = Tree
for i in formulalist:
if i == '(':
currentTree.insertLeft('')
rootStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in ['+', '-', '*', '/', ')']:
currentTree.setRootVal(int(i))
parent = rootStack.pop()
cerrentTree = parent
elif i in ['+', '-', '*', '/']:
currentTree.setRootVal(i)
currentTree.insertRight('')
rootStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = rootStack.pop()
else:
raise ValueError #raise的参数必须是一个异常实例或者一个异常类：ValueError无效参数
return Tree
def build_parse_tree(fpexpr):
fp_list = fpexpr.split()
pstack = Stack()
eTree = BinaryTree('')
pstack.push(eTree)
current_node = eTree
for i in fp_list:
if i == '(':
current_node.insert_left('')
pstack.push(current_node)
current_node = current_node.get_left_child()
elif i not in ['+', '-', '*', '/', ')']:
current_node.set_root_val(int(i))
parent = pstack.pop()
current_node = parent
elif i in ['+', '-', '*', '/']:
current_node = set_root_val(i)
current_node.insert_right('')
pstack.push(current_node)
current_node = current_node.get_right_child()
elif i == ')':
current_node = pstack.pop()
else:
raise ValueError
return eTree
def buildParseTree(fpexp):
fplist = fpexp.split()
# 输入时必须有空格
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
# pStack 用于存储父节点 调用时pop()
currentTree = eTree
for i in fplist:
# 要求输入时有空格
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in ['+', '-', '*', '/', ')']:
currentTree.setRootVal(int(i))
parent = pStack.pop()
currentTree = parent
elif i in ['+', '-', '*', '/']:
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def buildParseTree(fpexp):
fplist = fpexp.split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
for item in fplist:
if item == "(":
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif item.isnumeric():
currentTree.setRootVal(int(item))
currentTree = pStack.pop()
elif item in '+-/*':
currentTree.setRootVal(item)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif item == ')':
currentTree = pStack.pop()
else:
raise ValueError("token '{}' is not a valid integer".format(item))
return eTree
def buildParseTree(fpexp):
fplist = fpexp.split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
for i in fplist:
if i == "(":
currentTree.insertLeft("")
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i in ["+", "-", "*", "/"]:
currentTree.setRootVal(i)
currentTree.insertRight("")
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i not in ["+", "-", "*", "/", ")"]:
currentTree.setRootVal(i)
parent = pStack.pop()
currentTree = parent
elif i == ")":
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def buildParseTree(fpexp):
fplist = str(fpexp).split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
for i in fplist:
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i.upper() in ['+', '-', '*', '/', 'TRUE',
'FALSE']: #added true and false
currentTree.setRootVal(i.upper())
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i not in ['+', '-', '*', '/', ')']:
currentTree.setRootVal(int(i))
parent = pStack.pop()
currentTree = parent
elif i == ')':
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def construyeArbol(sufijoInv):
arbol = Arbol()
raiz = Nodo(sufijoInv[0], 'raiz')
arbol.agregar(raiz)
for a in range(1, len(sufijoInv)):
nodo = Nodo(sufijoInv[a])
if arbol.nodos[-1].derecha is None:
arbol.agregar(nodo, 'derecha')
else:
arbol.agregar(nodo, 'derecha')
def buildParseTree(fpexp):
"""
fpexp = "( ( 10 + 5 ) * 3 )"
pt = buildParseTree(fpexp)
"""
fplist = fpexp.split()
## 用來儲存父節點
## parent stack
pStack = Stack()
## 因為 Class() 是傳址 (reference type)
## 所以 eTree 和 currentTree 會是同一個 address
## 因此對 currentTree 所做的操作，會同樣影響 eTree！
##
## 附註：int, ... 是傳值 (value type)
eTree = BinaryTree('')
## pStack: 紀錄父節點
pStack.push(eTree)
## 傳址 (reference type)
currentTree = eTree
operator = ["+", "-", "*", "/"]
not_numbers = operator + ['(', ')']
for i in fplist:
if i == "(":
## 插入左子樹，並將 current 移到左子樹
## 此時 eTree 亦同樣插入左子樹
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in not_numbers:
## 如果是數字
## 則把該節點的值設定為 i
## 並利用 pStack 退回到該節點的父節點
currentTree.setRootVal(int(i))
parent = pStack.pop()
currentTree = parent
elif i in operator:
## 如果是運算子
## 則設定該節點為運算子後
## 插入右子樹
currentTree.setRootVal(i)
currentTree.insertRight('')
pStack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ")":
## 如果是 ")"
## 再往上退到該節點的父節點
currentTree = pStack.pop()
else:
raise ValueError
return eTree
def set_tree(text):
wtext = text.split()
pStack = Stack()
eTree = BinaryTree('')
pStack.push(eTree)
currentTree = eTree
currentTree.insertLeft('')
currentTree = currentTree.getLeftChild()
currentTree.setRootVal('1')
pStack.push(currentTree)
for i in wtext:
if BinaryTree.getRootVal(
currentTree) == '1' and not currentTree.isLeaf():
currentTree = pStack.pop()
currentTree.insertRight('')
currentTree = currentTree.getRightChild()
currentTree.setRootVal('2')
pStack.push(currentTree)
if i == '(':
currentTree.insertLeft('')
pStack.push(currentTree)
currentTree = currentTree.getLeftChild()
elif i not in ['(', ')']:
if currentTree.isLeaf():
if BinaryTree.getRootVal(currentTree) != '':
currentTree = pStack.pop()
currentTree.insertRight('')
currentTree = currentTree.getRightChild()
currentTree.setRootVal(i)
elif BinaryTree.getRootVal(currentTree) != None:
currentTree.setRootVal(i)
pStack.push(currentTree)
elif i == ')':
currentTree = pStack.pop()
currentTree = pStack.pop()
else:
raise ValueError
return eTree
class BinaryTree(object):
def __init__(self, root_obj):
self.key = root_obj
self.left_child = None
self.right_child = None
def insert_left(self, new_node):
if self.left_child == None:
self.left_child = BinaryTree(new_node)
else:
t = BinaryTree(new_node)
t.left_child = self.left_child
self.left_child = t
def insert_right(self, new_node):
if self.right_child == None:
self.right_child = BinaryTree(new_node)
else:
t = BinaryTree(new_node)
t.right_child = self.right_child
self.right_child = t
def get_right_child(self):
return self.right_child
def get_left_child(self):
return self.left_child
def get_root_val(self):
return self.key
def set_root_val(self, obj):
self.key = obj
def preorder(self):
print(self.key)
if self.left_child:
self.left_child.preorder()
if self.right_child:
self.right_child.preorder()
def buildParseTree(expr):
expr = expr.split()
binaryTree = BinaryTree('')
stack = Stack()
stack.push(binaryTree) # 避免空栈弹出时报错
currentTree = binaryTree
for i in expr:
if i == '(':
currentTree.insertLeft('')
stack.push(currentTree)
currentTree = binaryTree.getLeftChild()
elif i not in ['+', '-', '*', '/', ')']:
currentTree.setRootVal(int(i)) # 非数字int()就会报错
currentTree = stack.pop()
elif i in ['+', '-', '*', '/']:
currentTree.setRootVal(i)
currentTree.insertRight('')
stack.push(currentTree)
currentTree = currentTree.getRightChild()
elif i == ')':
currentTree = stack.pop()
else:
raise ValueError
return binaryTree
# binary tree or not
from pythonds.trees.binaryTree import BinaryTree
prev=None
def isBinarySearchTree(root):
global prev
if root:
if not isBinarySearchTree(root.leftChild):
return False
if (prev and prev.key>root.key):
return False
prev=root
if not isBinarySearchTree(root.rightChild):
return False
return True
tree=BinaryTree(4)
tree.insertLeft(2)
tree.insertRight(5)
ls=tree.getLeftChild()
ls.insertLeft(1)
ls.insertRight(3)
print isBinarySearchTree(tree)
def build_parse_tree(fpexp):
fplist = fpexp.split()
for i in fplist:
if i.__contains__('(') and i != '(':
index = fplist.index(i)
i_l = i.split('(')
fplist[index] = i_l[-1]
for j in range(len(i_l)-1):
fplist.insert(index, '(')
if i.__contains__(')') and i != ')':
index = fplist.index(i)
i_l = i.split(')')
fplist[index] = i.split(')')[0]
for j in range(len(i_l)-1):
fplist.insert(index+1, ')')
pstack = Stack()
current_tree = BinaryTree('')
current_tree.insertLeft('')
pstack.push(current_tree)
current_tree = current_tree.getLeftChild()
for i in fplist:
if i == '(':
current_tree.insertLeft('')
pstack.push(current_tree)
current_tree = current_tree.getLeftChild()
elif i not in ['and', 'or', ')']:
current_tree.setRootVal(i)
parent = pstack.pop()
current_tree = parent
elif i in ['and', 'or']:
if current_tree.getRootVal() != "":
pstack.push(current_tree)
current_tree = BinaryTree('')
current_tree.leftChild = pstack.pop()
current_tree.setRootVal(i)
current_tree.insertRight('')
pstack.push(current_tree)
current_tree = current_tree.getRightChild()
elif i == ')':
current_tree = pstack.pop()
else:
raise ValueError
return current_tree
from pythonds.trees.binaryTree import BinaryTree
import operator
x = BinaryTree('*')
x.insertLeft('+')
l = x.getLeftChild()
l.insertLeft(4)
l.insertRight(5)
x.insertRight(7)
def printexp(tree):
sVal = ""
if tree:
sVal = '(' + printexp(tree.getLeftChild())
sVal = sVal + str(tree.getRootVal())
sVal = sVal + printexp(tree.getRightChild())+')'
return sVal
def postordereval(tree):
opers = {'+':operator.add, '-':operator.sub, '*':operator.mul, '/':operator.truediv}
res1 = None
res2 = None
if tree:
res1 = postordereval(tree.getLeftChild())
res2 = postordereval(tree.getRightChild())
if res1 and res2:
return opers[tree.getRootVal()](res1,res2)
else:
return tree.getRootVal()
