Find all vehicles that are either `type: "truck"` OR have `year` less than `2015`.

Problem Statement

<p>Find all vehicles that are either <code>type: "truck"</code> OR have <code>year</code> less than <code>2015</code>.</p>

Examples

Input: vehicles collection: +-----+--------+-------+------+ | _id | make | type | year | +-----+--------+-------+------+ | 1 | Toyota | sedan | 2020 | | 2 | Ford | truck | 2019 | | 3 | Honda | sedan | 2012 | | 4 | Chevy | SUV | 2022 | +-----+--------+-------+------+

Output: +-----+-------+-------+------+ | _id | make | type | year | +-----+-------+-------+------+ | 2 | Ford | truck | 2019 | | 3 | Honda | sedan | 2012 | +-----+-------+-------+------+

Explanation: The query retrieves all documents from the collection that satisfy the specified filter criteria.

Complexity

Time Complexity: -

Space Complexity: -

Hints

💡 Hint 1: Use comparison operators ($gt, $gte, $lt, $lte) to filter documents based on numeric or date ranges. 💡 Hint 2: Construct the filter condition: { fieldName: { $gt: value } } inside db.<collection>.find(...). 💡 Hint 3: Chain projection or sorting if requested, and invoke .toArray() to produce the result array.

Editorial & Approach

Problem Overview & Intuition

To solve "Logical OR ($or)", we query the MongoDB document store. The goal is to find all vehicles that are either `type: "truck"` or have `year` less than `2015`. 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.vehicles.find({ $or: [{ type: "truck" }, { year: { $lt: 2015 } }] }).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.

Logical OR ($or)

Easy

Find all vehicles that are either type: "truck" OR have year less than 2015.

Example Scenarios

1Example 1

Input:

vehicles collection

_id	make	type	year
1	Toyota	sedan	2020
2	Ford	truck	2019
3	Honda	sedan	2012
4	Chevy	SUV	2022

Output:

_id	make	type	year
2	Ford	truck	2019
3	Honda	sedan	2012

Explanation:

The query retrieves all documents from the collection that satisfy the specified filter criteria.

MongoDB Editor

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Query Results (JSON)

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