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Java-based LeetCode algorithm problem solutions, regularly updated
2882\. Drop Duplicate Rows
Easy
DataFrame customers
+-------------+--------+
| Column Name | Type |
+-------------+--------+
| customer_id | int |
| name | object |
| email | object |
+-------------+--------+
There are some duplicate rows in the DataFrame based on the `email` column.
Write a solution to remove these duplicate rows and keep only the **first** occurrence.
The result format is in the following example.
**Example 1:**
**Input:**
+-------------+---------+---------------------+
| customer_id | name | email |
+-------------+---------+---------------------+
| 1 | Ella | [email protected] |
| 2 | David | [email protected] |
| 3 | Zachary | [email protected] |
| 4 | Alice | [email protected] |
| 5 | Finn | [email protected] |
| 6 | Violet | [email protected] |
+-------------+---------+---------------------+
**Output:**
+-------------+---------+---------------------+
| customer_id | name | email |
+-------------+---------+---------------------+
| 1 | Ella | [email protected] |
| 2 | David | [email protected] |
| 3 | Zachary | [email protected] |
| 4 | Alice | [email protected] |
| 6 | Violet | [email protected] |
+-------------+---------+---------------------+
**Explanation:** Alic (customer_id = 4) and Finn (customer_id = 5) both use [email protected], so only the first occurrence of this email is retained.