Get all distinct `department` values from the `employees` collection.

Problem Statement

<p>Get all distinct <code>department</code> values from the <code>employees</code> collection.</p>

Examples

Input: employees collection: +-----+---------+-------------+ | _id | name | department | +-----+---------+-------------+ | 1 | Alice | Engineering | | 2 | Bob | Marketing | | 3 | Charlie | Engineering | | 4 | Dana | Sales | +-----+---------+-------------+

Explanation: The target document is modified according to the update operators and the updated document is returned.

Complexity

Time Complexity: -

Space Complexity: -

Hints

💡 Hint 1: Use db.<collection>.find(<filter>) to query the documents in the collection. 💡 Hint 2: Pass an empty object {} to retrieve all documents, or specify key-value pairs for exact matching. 💡 Hint 3: Chain .toArray() to resolve the MongoDB cursor into a JavaScript array: return db.<collection>.find(...).toArray();

Editorial & Approach

Problem Overview & Intuition

To solve "Get Distinct Values (distinct)", we query the MongoDB document store. The goal is to get all distinct `department` values from the `employees` collection. Using a targeted find query, the database engine filters and structures the BSON documents efficiently.

Step-by-Step Approach

Identify Target Collection: Access the collection through the db instance.
Construct Query / Pipeline: Build the query filter with appropriate comparison operators.
Resolve Cursor: Invoke .toArray() to transform the query cursor into the required array of documents.

Optimal Implementation (MongoDB)

function solve(db) {
  return db.employees.distinct("department");
}

Complexity Analysis

Time Complexity O(N) collection scan (O(log N) if index is present on filtered fields).

Space Complexity O(K) where K is the number of returned documents in memory.

Key Considerations & Edge Cases

Empty Collections: If no documents match, the query cleanly returns an empty array [].
Missing / NULL Fields: Missing fields in documents are handled safely without throwing runtime exceptions.
Type Coercion: BSON types (ObjectId, Numbers, Strings) are compared strictly according to MongoDB specifications.

Get Distinct Values (distinct)

Easy

Get all distinct department values from the employees collection.

Example Scenarios

1Example 1

Input:

employees collection

_id	name	department
1	Alice	Engineering
2	Bob	Marketing
3	Charlie	Engineering
4	Dana	Sales

Output:

result
Engineering
Marketing
Sales

Explanation:

The target document is modified according to the update operators and the updated document is returned.

MongoDB Editor

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Query Results (JSON)

Run your MongoDB code to see results here.