Check for Balanced Brackets in an expression using Stack

parenthesis-checker.py

# Python3 program to check for 
# balanced brackets. 

# function to check if 
# brackets are balanced 


def areBracketsBalanced(expr): 
	stack = [] 

	# Traversing the Expression 
	for char in expr: 
		if char in ["(", "{", "["]: 

			# Push the element in the stack 
			stack.append(char) 
		else: 

			# IF current character is not opening 
			# bracket, then it must be closing. 
			# So stack cannot be empty at this point. 
			if not stack: 
				return False
			current_char = stack.pop() 
			if current_char == '(': 
				if char != ")": 
					return False
			if current_char == '{': 
				if char != "}": 
					return False
			if current_char == '[': 
				if char != "]": 
					return False

	# Check Empty Stack 
	if stack: 
		return False
	return True


# Driver Code 
if __name__ == "__main__": 
	expr = "{()}[]"

	# Function call 
	if areBracketsBalanced(expr): 
		print("Balanced") 
	else: 
		print("Not Balanced")