Flatten a nested JSON object
Company: Salesforce
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Onsite
## Problem
You are given a JSON-like value representing an object that may contain:
- **Objects / dictionaries** (string keys)
- **Arrays / lists**
- **Primitive values** (string/number/boolean/null)
Return a **flattened map** from *path* to *primitive value*.
### Path rules
- Use `.` to join object keys.
- Use `[i]` for array indices.
- The root has no leading separator.
### Examples
**Input**
```json
{
"a": 1,
"b": {"c": 2, "d": [3, 4]},
"e": [ {"f": 5}, 6 ]
}
```
**Output**
```text
a -> 1
b.c -> 2
b.d[0] -> 3
b.d[1] -> 4
e[0].f -> 5
e[1] -> 6
```
### Notes / constraints
- Keys are strings and may contain any characters except `.` and `[` `]` (you may assume this to avoid escaping).
- The output can be returned as a dictionary/map of `string -> primitive`.
- Order does not matter.
Implement a function to perform this flattening.
Quick Answer: This question evaluates the ability to traverse and manipulate nested JSON-like structures, emphasizing concepts such as recursion or iterative traversal, array indexing, and path string construction; it tests data structures and serialization knowledge within the Coding & Algorithms domain and targets practical implementation skills for a software engineer role. It is commonly asked to assess how interviewees flatten hierarchical payloads for data processing or API normalization, reason about mixed object/array edge cases, and map hierarchical paths to primitive values.