Implement nested object path lookup

Implement a function `get(obj, path)` for a nested data structure composed only of maps and arrays. Path rules: - `.` accesses a map key - `[i]` accesses an array index - keys do not contain `.` or brackets - example path syntax: `ab[1].c.d[2][13]` Return the value at the given path. If any key is missing, an index is out of bounds, or the path does not match the actual type at some step, return `null`. Examples: - `get({"a": {"b": [10, 20]}}, "a.b[1]") -> 20` - `get({"a": {"b": [10, 20]}}, "a.b[3]") -> null` Write the function and analyze its time and space complexity.