Balanced Parentheses Problem Using Stack in DSA C - Build from Scratch

Balanced Parentheses Problem Using Stack

📖 Scenario: Imagine you are building a simple code editor that checks if the parentheses in a line of code are balanced. Balanced parentheses mean every opening bracket has a matching closing bracket in the correct order.

🎯 Goal: You will create a program that uses a stack to check if a given string of parentheses is balanced or not.

📋 What You'll Learn

Create a stack data structure using an array and an integer top pointer.

Use a configuration variable to store the input string of parentheses.

Implement the logic to push and pop from the stack to check for balanced parentheses.

Print Balanced if parentheses match correctly, otherwise print Not Balanced.

💡 Why This Matters

🌍 Real World

Checking balanced parentheses is important in code editors and compilers to ensure code syntax is correct.

💼 Career

Understanding stacks and balanced parentheses is a common interview question and a fundamental concept in programming.

1

Create the stack data structure

Create an integer array called stack of size 100 and an integer variable top initialized to -1.

DSA C

# Create the stack array and top variable
# Your code here

Hint

The stack is an array and top keeps track of the last filled position. Start top at -1 to show the stack is empty.

2

Add the input parentheses string

Create a character array input initialized with the string "(()())".

DSA C

int stack[100];
int top = -1;

// Create the input string
# Your code here

Hint

The input string contains parentheses to check. Use double quotes for the string.

3

Implement the balanced parentheses check logic

Write a for loop using i to iterate over input until the null character. Inside the loop, push '(' onto stack by increasing top when found. When ')' is found, pop from stack by decreasing top. If top is -1 when popping, break the loop early.

DSA C

int stack[100];
int top = -1;

char input[] = "(()())";

// Loop through input and use stack to check parentheses
# Your code here

Hint

Use top++ to push and top-- to pop. Check for unmatched closing parentheses by seeing if top is -1 before popping.

4

Print if parentheses are balanced or not

After the loop, print Balanced if top is -1, otherwise print Not Balanced.

DSA C

int stack[100];
int top = -1;

char input[] = "(()())";

for (int i = 0; input[i] != '\0'; i++) {
    if (input[i] == '(') {
        stack[++top] = '(';
    } else if (input[i] == ')') {
        if (top == -1) {
            break;
        } else {
            top--;
        }
    }
}

// Print result based on top value
# Your code here

Hint

If the stack is empty at the end (top == -1), parentheses are balanced. Otherwise, they are not.