Operating Stacks in Python: Practical Problem-Solving Approach
Introduction
Hello learners, are you ready for another exciting session? Today, we are diving deeper into understanding how to operate Stacks in Python by solving problems that often appear in coding interviews or even real-world projects. Let's get ready to solve some Stack-based problems and enhance your problem-solving skills with stacks!
Problem 1: Are Brackets Balanced?
Let's start with a common coding challenge - checking if the brackets in a string are balanced. Imagine that the string is the source code of a software application, and these brackets are the open and close statements for loops, if-else conditions, or function blocks in the source code. For the code to be valid and runnable, every open statement (bracket) must have a corresponding close statement (bracket) in the proper order.
Problem Actualization
To make this problem more relatable, let's consider this real-world scenario. You are part of a team developing a text editor for programming languages. As a value-added feature, you want to provide real-time feedback to the users of your text editor about the number of unbalanced brackets in their code to assist them in avoiding syntax errors. This problem accurately mimics such a feature where we are given a string of code, and our task is to check if all the brackets in the code are balanced.
Naive Approach and Its Limitations
If we consider a simple way to approach this problem, we could initialize a counter variable for each type of bracket (parentheses, braces, and square brackets), increment the counters when we encounter an opening bracket, and decrement it when we get a closing bracket. Although this approach checks whether we have a closing bracket for every opening bracket, it completely misses one critical aspect - the order of brackets. For the brackets to be considered balanced, every closing bracket must correspond to the most recently opened bracket of the same type, which is not checked in this approach.
Efficient Approach Explanation
An efficient way to solve this problem is by using a stack data structure. The stack follows the LIFO (Last In, First Out) principle, which makes it highly suitable when we want to track the opening and closing brackets' order, as the most recently opened bracket needs to be closed first before we move on to the next opening bracket.
