Validate a bracket string
Company: Bytedance
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
Given a string `s` containing only the characters `'('`, `')'`, `'{'`, `'}'`, `'['`, and `']'`, determine whether the input string is valid.
A string is valid if:
1. Every opening bracket has a corresponding closing bracket of the same type.
2. Brackets are closed in the correct order.
3. Every closing bracket matches the most recent unmatched opening bracket.
Return `true` if `s` is valid; otherwise return `false`.
Example:
- Input: `"()[]{}"` → Output: `true`
- Input: `"([)]"` → Output: `false`
Quick Answer: This question evaluates understanding of stack data structures, string parsing, and matching logic for balanced brackets and parentheses. It is commonly asked in technical interviews within the Coding & Algorithms domain to assess the ability to produce correct and efficient bracket-matching logic, testing practical application of data-structure implementation alongside conceptual understanding of stack behavior and edge-case handling.