I need assistance here, please.

Question

Parentheses are balanced, if all opening parentheses have their corresponding closing parentheses.

Given an expression as input, we need to find out whether the parentheses are balanced or not.
For example, "(x+y)*(z-2*(6))" is balanced, while "7-(3(2*9))4) (1" is not balanced.

The problem can be solved using a stack.
Push each opening parenthesis to the stack and pop the last inserted opening parenthesis whenever a closing parenthesis is encountered.
If the closing bracket does not correspond to the opening bracket, then stop and say that the brackets are not balanced.
Also, after checking all the parentheses, we need to check the stack to be empty -- if it's not empty, then the parentheses are not balanced.

Implement the balanced() function to return True if the parentheses in the given expression are balanced, and False if not.

Sample Input:
(a( ) eee) )

Sample Output:
False
https://code.sololearn.com/crdP8KlKuOso/?ref=app

Answer 1

Yes. You can check list is not empty before pop.
Or in other way, if you know about, try ctach, on empty list, pop opearation raise error. So try catch will help to return false.
But the first thing easy
if len(list) == 0 :
return false
else : list.pop()

Answer 2

Frimpong Godfred You could first check if the list is empty (before pop). If it not should you can already return false.

Answer 3

These two have not work in any way..
if '(' or ')' is i: it is always true.
May you trying is
if i in ( '(', ')' ) :
Or
if i=='(' or i== ')' :

return len(list) == None, always return false since input have at least a charecter and it is added to list. You never tried to pop elements..
Also len() never returns None. it rerun a number (0 or length)

Try this way:
** take input
** if input's charecter '(' , add to list
** if input's charecter is ')' pop from list. If not successful return false

** if list is empty, return true else return false...

Hope it helps...

Answer 4

Jayakrishna🇮🇳
I don't get it.
If it's '(' , I add it to the list. Bur when it's ')' , how can I pop it out of the list when I've not added it to the list yet.

Answer 5

Thank you guys Jayakrishna🇮🇳 and JaScript

I figured it out

https://code.sololearn.com/crdP8KlKuOso/?ref=app