Validate JSON against a protobuf-like schema
Company: Applied
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
You are given a simplified protobuf-like schema definition and a JSON value. Determine whether the JSON conforms to the schema.
## Schema model
- A **schema** contains named **message types**.
- Each message type contains **fields**. Each field has:
- `name` (string)
- `type` (one of: `int`, `float`, `bool`, `string`, or another message type name)
- `optional` (boolean)
Assume:
- The JSON root is an **object** corresponding to a specified root message type.
- A **required** field (`optional = false`) must be present.
- An **optional** field may be missing.
- If a field is present, its JSON value must match the expected type:
- `int`: JSON number with no fractional part
- `float`: JSON number (integer values are allowed)
- `bool`: JSON boolean
- `string`: JSON string
- message type: JSON object that recursively validates against that message
- Extra JSON keys not in the schema make the JSON invalid.
## Task
Implement `isValid(schema, rootTypeName, jsonValue) -> bool`.
## Constraints
- Up to ~10^4 total fields across all message types.
- Message nesting depth is bounded (e.g., ≤ 50).
## Example
Schema:
- `User { id:int (required), name:string (optional) }`
Valid JSON: `{ "id": 1 }`
Invalid JSON: `{ "name": "a" }` (missing required `id`)
Invalid JSON: `{ "id": 1, "age": 10 }` (unknown field `age`)
Quick Answer: This question evaluates schema validation and data-typing skills, including understanding of JSON primitive types, recursive message structures, and conformance to a protobuf-like schema with required and optional fields.