Balanced Parentheses Not working

Question

I have this code in a problem called balanced parentheses. The goal of the problem is to find balanced parentheses. For instance "(x+y)*(z-2*(6))" is balanced and "7-(3(2*9))4) (1" is not.

I am passing 6 test cases but I can't pass the last one.

Can you help me by solving the problem? Thanks in advance

`class Stack:
def __init__(self):
self.items = []

def isEmpty(self):
return self.items == []

def push(self, item):
self.items.append(item)

def pop(self):
return self.items.pop()

def peek(self):
return self.items[len(self.items)-1]

def size(self):
return len(self.items)

def balanced(expression):
a = Stack()
for i in expression:
if i == "(":
a.push(i)
for i in expression:
if i == ")":
if a.size() == 0:
return False
else:
a.pop()
if a.size() == 0:
return True
else:
return False

print(balanced(input()))`

Answer 1

I tested ")(". It should return False, but in you current code it returns True.
I'm not sure but something like this could be the reason the test case fails?

Answer 2

Thanks i got it

Answer 3

Hi, you have a lot of code in the description. Can you put it on playground and link it here?

Answer 4

Sure I can but can you name one? Sorry i don't know any

Answer 5

I mean something like this:

https://code.sololearn.com/cUK6Jt1b0wUQ/?ref=app

Answer 6

https://code.sololearn.com/cA158A6a0a25

Answer 7

I changed it and it works so if anyone needs it you can find it in the link

Answer 8

class Stack:
def __init__(self):
self.items = []

def push(self, item):
self.items.insert(0, item)

def pop(self):
try:
return self.items.pop(0)
except:
par.push(")")

def is_empty(self):
if self.items == []:
return True
else:
return False

prompt = input()

par = Stack()

for c in prompt:
if c == "(":
par.push("(")
elif c == ")":
par.pop()

print(par.is_empty())

Answer 9

my code that properly worked and passed all the cases:
def Balanced(exp):
i = exp.find (")")
j = exp.find ("(")
if i < 0 and j < 0:
return True
if i < 0 and j >= 0:
return False
if i >= 0 and j < 0:
return False
if i >= 0 and j >= 0:
if i < j:
return False
else:
s = list ()
counter_2 = 0
for c in exp:
if c == "(":
s.insert (0,"(")
if c == ")":
if len (s) > 0:
s.pop(0)
else:
s.insert (0, ")")
if len (s) == 0:
return True
if len (s) > 0:
if s[0] == "(" or s[0] == ")":
return False
else:
return True
else:
if s[0] == "(":
return False
print (Balanced)

print (Balanced(input()))