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Consider the 4 possibilities. The object could be an array, an object, a string, or another type.
Think about the problem recursively. If you know how to convert any sub-data into a string, how could you use it to convert the entire data into a string?
If the data is a string, it's just the value surrounded by double quotes. If the data is another type, its just String(data). If the data is an array, it's the recursively stringified value of each item separated by commas. If the data is an object, it's a series of key-value pairs where each value is the recursively stringified value.
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Problems involving manual serialization or recursive object traversal can appear in technical interviews. They test understanding of recursion, data structures, and how structured data formats like JSON are constructed.
Recursion with standard object and array traversal works best. By iterating through object key–value pairs and array elements, you can build the JSON string step by step while handling nested structures correctly.
The optimal approach is to use recursion to traverse the structure and serialize each value type. Primitive values are converted directly, while arrays and objects recursively serialize their elements or properties to construct a valid JSON string.
The time complexity is O(n), where n is the total number of elements and properties in the structure. Each value is visited once during the recursive traversal, making the process linear.
