How can stacks be used to check for balanced parentheses in an expression?

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Question: How can stacks be used to check for balanced parentheses in an expression?

Options:

Correct Answer: By pushing opening parentheses onto the stack and popping for closing ones

Solution:

Stacks can be used to check for balanced parentheses by pushing opening ones and popping when a closing one is encountered.

How can stacks be used to check for balanced parentheses in an expression?

How can stacks be used to check for balanced parentheses in an expression?

Step 1: Initialize an empty stack to keep track of opening parentheses.
Step 2: Read the expression from left to right, one character at a time.
Step 3: If you encounter an opening parenthesis '(', push it onto the stack.
Step 4: If you encounter a closing parenthesis ')', check if the stack is empty.
Step 5: If the stack is empty when you find a closing parenthesis, it means there is no matching opening parenthesis, so the expression is unbalanced.
Step 6: If the stack is not empty, pop the top element from the stack (which should be the matching opening parenthesis).
Step 7: Continue this process until you have read the entire expression.
Step 8: After reading the expression, check the stack again. If it is empty, the parentheses are balanced. If it is not empty, they are unbalanced.

Stack Data Structure – A stack is a linear data structure that follows the Last In First Out (LIFO) principle, where elements are added and removed from the top.
Balanced Parentheses – An expression is considered to have balanced parentheses if every opening parenthesis has a corresponding closing parenthesis in the correct order.
Push and Pop Operations – In the context of stacks, 'push' adds an element to the top of the stack, while 'pop' removes the top element.