Python program to check matching of simple parentheses

Question

I am a Python newbie and I came across this exercise of checking whether or not the simple brackets \"(\", \")\" in a given string are matched evenly.

I have seen ex

Answer 1

In case u also need to find the position of the first mismatching bracket from left u can use the below code which also cover certain edge cases:

def isBalanced(expr):
    opening=set('([{')
    new=set(')]}{[(')
    match=set([ ('(',')'), ('[',']'), ('{','}') ])
    stack=[]
    stackcount=[]
    for i,char in enumerate(expr,1):
        if char not in new:
            continue
        elif char in opening:
            stack.append(char)
            stackcount.append(i)
        else:
            if len(stack)==0:
                print(i)
                return False
            lastOpen=stack.pop()
            lastindex=stackcount.pop()
            if (lastOpen, char) not in match:
                print (i)
                return False
    length=len(stack)
    if length!=0:
      elem=stackcount[0]
      print (elem)
    return length==0
string =input()
ans=isBalanced(string)
if ans==True:
    print("Success")