Implement page 2 with page size 2: skip the first 2 items and return the next 2 from the `inventory` collection.

Problem Statement

<p>Implement page 2 with page size 2: skip the first 2 items and return the next 2 from the <code>inventory</code> collection.</p>

Examples

Input: inventory collection: +-----+--------+-----+ | _id | item | qty | +-----+--------+-----+ | 1 | Pencil | 100 | | 2 | Pen | 50 | | 3 | Eraser | 200 | | 4 | Ruler | 75 | | 5 | Marker | 30 | +-----+--------+-----+

Output: +-----+--------+-----+ | _id | item | qty | +-----+--------+-----+ | 3 | Eraser | 200 | | 4 | Ruler | 75 | +-----+--------+-----+

Explanation: The query restricts and skips documents to return the specified subset.

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 "Pagination (Skip + Limit)", we query the MongoDB document store. The goal is to implement page 2 with page size 2: skip the first 2 items and return the next 2 from the `inventory` 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.inventory.find({}).skip(2).limit(2).toArray();
}

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.

Pagination (Skip + Limit)

Easy

Implement page 2 with page size 2: skip the first 2 items and return the next 2 from the inventory collection.

Example Scenarios

1Example 1

Input:

inventory collection

_id	item	qty
1	Pencil	100
2	Pen	50
3	Eraser	200
4	Ruler	75
5	Marker	30

Output:

_id	item	qty
3	Eraser	200
4	Ruler	75

Explanation:

The query restricts and skips documents to return the specified subset.

MongoDB Editor

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Query Results (JSON)

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