Stack Exercise - Python

perChecker.py

## (5+6)*(7+8)/(4+3)  #Checking Bracket with Stack
## from stack (FileName) (stack.py) import Stack (class)

from stack import Stack
def perChecker(symbolString):
    s = Stack()
    balanced = True
    index = 0 
    while index < len(symbolString) and balanced:
        symbol = symbolString[index]
        if symbol == "(":
            s.push(symbol)
        else:
            if s.is_empty():
                balanced = False
            else:
                s.pop()
        index = index + 1
    if balanced and s.is_empty():
        return True
    else: 
        return False 

print(perChecker('(())'))
print(perChecker('('))

stack.py

class Stack:
    def __init__(self):
        self.items = [] # Empty Array
    def is_empty(self):
        return self.items == [] # Check Stack is Empty or Not
    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)

s = Stack() # creating object of the class

print(s.is_empty())

s.push(4)
s.push("dog")
print(s.peek())

s.push("duck")
print(s.size())

s.push("cat")

print(s.pop()) #cat
print(s.pop()) #true
print(s.size())
print("=======")
s2 = Stack()
s.push("tiger")
print(s.peek())
print(s.size())