task: #3554

README.md

@@ -195,6 +195,7 @@ Useful for preparing for technical interviews and improving your SQL skills.
     - [601. Human Traffic of Stadium](./leetcode/hard/601.%20Human%20Traffic%20of%20Stadium.sql)
     - [3374. First Letter Capitalization II](./leetcode/hard/3374.%20First%20Letter%20Capitalization%20II.sql)
     - [3451. Find Invalid IP Addresses](./leetcode/hard/3451.%20Find%20Invalid%20IP%20Addresses.sql)
+    - [3554. Find Category Recommendation Pairs](./leetcode/hard/3554.%20Find%20Category%20Recommendation%20Pairs.sql)
 
 ## Contributing
 

leetcode/hard/3554. Find Category Recommendation Pairs.sql

@@ -0,0 +1,51 @@
+/*
+Question 3554. Find Category Recommendation Pairs
+Link: https://leetcode.com/problems/find-category-recommendation-pairs/description/?envType=problem-list-v2&envId=database
+
+Table: ProductPurchases
+
++-------------+------+
+| Column Name | Type | 
++-------------+------+
+| user_id     | int  |
+| product_id  | int  |
+| quantity    | int  |
++-------------+------+
+(user_id, product_id) is the unique identifier for this table. 
+Each row represents a purchase of a product by a user in a specific quantity.
+Table: ProductInfo
+
++-------------+---------+
+| Column Name | Type    | 
++-------------+---------+
+| product_id  | int     |
+| category    | varchar |
+| price       | decimal |
++-------------+---------+
+product_id is the unique identifier for this table.
+Each row assigns a category and price to a product.
+Amazon wants to understand shopping patterns across product categories. Write a solution to:
+
+Find all category pairs (where category1 < category2)
+For each category pair, determine the number of unique customers who purchased products from both categories
+A category pair is considered reportable if at least 3 different customers have purchased products from both categories.
+
+Return the result table of reportable category pairs ordered by customer_count in descending order, and in case of a tie, by category1 in ascending order lexicographically, and then by category2 in ascending order.
+*/
+
+SELECT
+    p1.category AS category1,
+    p2.category AS category2,
+    COUNT(DISTINCT pp2.user_id) AS customer_count
+FROM ProductInfo AS p1
+CROSS JOIN ProductInfo AS p2
+RIGHT JOIN --noqa: CV08
+    ProductPurchases AS pp1
+    ON p1.product_id = pp1.product_id
+RIGHT JOIN --noqa: CV08
+    ProductPurchases AS pp2
+    ON p2.product_id = pp2.product_id AND pp1.user_id = pp2.user_id
+WHERE p1.category < p2.category
+GROUP BY p1.category, p2.category
+HAVING COUNT(DISTINCT pp2.user_id) >= 3
+ORDER BY customer_count DESC, p1.category  ASC, p2.category ASC