Validate JSON String

Problem Statement
The "Validate JSON String" interview question, commonly attributed to Microsoft interviews with tags String, Stack, and Parsing, requires implementing a function isValidJsonStructure(s) -> bool that checks the structural validity of a given string s intended as JSON text. This focuses on proper nesting and matching of brackets {, }, [, ] while correctly handling quoted strings (where brackets inside quotes are ignored) and basic escape sequences like \". It does not validate full JSON semantics like keys, values (true/false/null), or data types—only structural elements using a stack-based parser.[1][9]

Key Rules

• Top-level structure must be {...} or [...].
• Empty structures {} and [] are valid.
• Content like "...", { }, [ ] inside is ignored for nesting checks.
• Inside quoted strings, brackets do not count toward nesting (e.g., \\\" escapes quotes but doesn't close strings prematurely).
• Unmatched brackets, unclosed quotes, or bad nesting return false.
  Constraints: 1 <= len(s) <= 10^5 (efficient O(n) time expected via stack).[1]

Input/Output Examples
| Input String | Output | Explanation |
|-------------------------------|--------|--------------------------------------------------|
| "{\"a\":[1,2,3]}" | true | Valid nesting; brackets in string ignored. [1]|
| "{[}]" | false| Bad nesting (object inside array mismatch). [1]|
| "{\"x\":\"[}\" }" | true | Brackets inside quoted string ignored. [1] |
| "{\"a\":\"unterminated" | false| Unclosed quote. [1] |
| "{}" or "[]" | true | Empty valid structures. [1] |
| "true" | false| Lacks required bracket structure. [1] |

Approach Overview
Traverse the string with a stack for open brackets. Track quote state to skip inner brackets. Push opens ({, [), pop on matching closes, ignore inside quotes/escapes. Final stack empty + no open quotes = valid.[1]