🦄 Parens Oracle: Valid Parentheses

Difficulty: Beginner Tags: stack, strings, validation, matching Series: CS 102: Problem Solving & Logic

Problem

In the mystical realm of code, the Oracle guards the balance of parentheses. Your task is to validate whether a string of brackets is properly balanced.

Given a string containing only the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

A string is valid if: 1. Every opening bracket has a corresponding closing bracket of the same type 2. Opening brackets are closed in the correct order 3. Every closing bracket has a corresponding opening bracket of the same type

Real-World Application

Bracket validation appears in: - Code editors - syntax validation, auto-completion - Compilers - parsing expressions and code blocks - Markup languages - HTML/XML tag matching - Mathematical expressions - validating formulas - Configuration files - JSON/YAML validation - Regular expressions - pattern validation - Text editors - bracket highlighting and matching

Input

data = str  # String containing only brackets: ()[]{}

Output

bool  # True if valid, False otherwise

Constraints

• String length ≤ 100,000
• String contains only bracket characters
• Empty string is considered valid

Examples

Example 1: Simple Valid

Input: "()[]{}"

Output: True

Explanation: - () - valid pair - [] - valid pair - {} - valid pair - All balanced and in order

Example 2: Mismatched Type

Input: "(]"

Output: False

Explanation: - ( opens, but ] is wrong closing type - Not valid

Example 3: Nested Valid

Input: "([{}])"

Output: True

Explanation: - ( opens - [ opens (nested) - { opens (nested deeper) - } closes { ✓ - ] closes [ ✓ - ) closes ( ✓ - Proper nesting order

Example 4: Wrong Order

Input: "([)]"

Output: False

Explanation: - ( opens, [ opens - ) tries to close (, but [ is still open - Wrong closing order

Example 5: Unclosed

Input: "("

Output: False

Explanation: - Opening bracket with no closing - Not valid

Example 6: Empty String

Input: ""

Output: True

Explanation: - Empty string is considered valid - No unbalanced brackets

Example 7: Only Closing

Input: ")"

Output: False

Explanation: - Closing bracket with no opening - Not valid

What You'll Learn

• Stack-based problem solving
• Matching pairs with LIFO (Last-In-First-Out) order
• Using hash maps for lookup
• Early exit optimization

Why This Matters

This is a top 10 coding interview question that tests: - Understanding of stack data structure - Pattern matching and validation - The LIFO principle - Ability to recognize when to use stacks

Starter Code

def challenge_function(data):
    """
    Validate if brackets are properly balanced and ordered.

    Args:
        data: string containing only brackets: ()[]{}

    Returns:
        bool: True if valid, False otherwise
    """
    # Your implementation here
    pass