Count Customers with Any High-Value Bill

Easy

A billing analytics team wants a quick metric showing how many unique customers have ever produced a high-value bill. Table: Store bill_id: unique bill identifier customer_id: identifier of the billed customer amount: billed amount for that bill Business rule: A customer is considered rich if they have at least one bill where amount > 500. Task: Return a single-row result with one column rich_count containing the number of rich customers. Output requirements: Return exactly one column: rich_count Return exactly one row Supported submission environments: SQL (SQLite 3.27.2) Pandas (Python)

Example 1

Input

Store:
| bill_id | customer_id | amount |
|---------|-------------|--------|
| 6       | 1           | 549    |
| 8       | 1           | 834    |
| 4       | 2           | 394    |
| 11      | 3           | 657    |
| 13      | 3           | 257    |

Output

[{"rich_count":2}]

Explanation

Customers 1 and 3 each have at least one bill above 500. Customer 2 does not.

Example 2

Input

Store:
| bill_id | customer_id | amount |
|---------|-------------|--------|
| 101     | 9           | 500    |
| 102     | 9           | 499    |
| 103     | 10          | 501    |
| 104     | 10          | 500    |
| 105     | 11          | 500    |

Output

[{"rich_count":1}]

Explanation

Only customer 10 qualifies because the threshold is strictly greater than 500.

Example 3

Input

Store:
[]

Output

[{"rich_count":0}]

Explanation

No bills means no customer can qualify as rich.

Constraints

0 <= number of rows in Store <= 900
1 <= bill_id <= 2000000000
1 <= customer_id <= 1000000000
0 <= amount <= 5000
bill_id values are unique
A rich customer is one with at least one row where amount > 500
Return exactly one output column named rich_count
Return exactly one output row
For SQL submissions, use SQLite 3.27.2 semantics
For Pandas submissions, return a DataFrame with one row and one column rich_count