Count how many movies have a `rating` greater than or equal to `8` using the find cursor `.count()` method.

Problem Statement

<p>Count how many <code>movies</code> have a <code>rating</code> greater than or equal to <code>8</code> using the find cursor <code>.count()</code> method.</p>

Examples

Input: movies collection: +-----+-------+--------+ | _id | title | rating | +-----+-------+--------+ | 1 | A | 9 | | 2 | B | 6 | | 3 | C | 8 | | 4 | D | 7 | +-----+-------+--------+

Output: +-------+ | count | +-------+ | 2 | +-------+

Explanation: The query calculates the total count of documents that satisfy the given 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 "Count with Cursor (.count)", we query the MongoDB document store. The goal is to count how many movies have a `rating` greater than or equal to `8` using the find cursor `.count()` method. 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.movies.find({ rating: { $gte: 8 } }).count();
}

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.

Count with Cursor (.count)

Easy

Count how many movies have a rating greater than or equal to 8 using the find cursor .count() method.

Example Scenarios

1Example 1

Input:

movies collection

_id	title	rating
1	A	9
2	B	6
3	C	8
4	D	7

Output:

count
2

Explanation:

The query calculates the total count of documents that satisfy the given filter criteria.

MongoDB Editor

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Query Results (JSON)

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