Balanced Brackets | Dataford Interview Questions

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Problem

Raptive ad markup can contain nested grouping symbols such as parentheses, square brackets, and braces. Given a string from a Raptive Creator Dashboard configuration, determine whether every bracket is correctly opened, matched, and closed.

A string is balanced when:

Every opening bracket has a corresponding closing bracket of the same type.
Brackets close in the reverse order in which they open.
Non-bracket characters, including letters, digits, spaces, and punctuation, are ignored.

Formal Specification

Implement is_balanced(markup).

Input: markup, a string containing zero or more ASCII characters.
Output: Return True if all brackets are balanced and properly nested; otherwise return False.
Bracket pairs: (), [], and {}.

Constraints

0 <= len(markup) <= 10^5
markup contains ASCII characters
Only (), [], and {} affect the result

Function Signature

def is_balanced(markup):