Check whether brackets are balanced

Problem

Given a string s that may contain bracket characters, determine whether the brackets are properly balanced.

Treat the following as brackets:

• Parentheses: ( and )
• Square brackets: [ and ]
• Curly braces: { and }

All other characters (letters, digits, spaces, punctuation) should be ignored.

A string is balanced if:

1. Every opening bracket is closed by the same type of bracket.
2. Brackets are closed in the correct order (proper nesting).

Input/Output

• Input: string s
• Output: boolean true if balanced, otherwise false

Examples

• "(a[b]{c})" → true
• "([)]" → false
• "((" → false
• "" → true

Constraints (assume)

• 0 ≤ len(s) ≤ 2 * 10^5