[Python/Pandas] 리트코드 1407. Top Travellers

문제

Table: Users
+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| id            | int     |
| name          | varchar |
+---------------+---------+

id is the column with unique values for this table.
name is the name of the user.

 Table: Rides
+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| id            | int     |
| user_id       | int     |
| distance      | int     |
+---------------+---------+

id is the column with unique values for this table.
user_id is the id of the user who traveled the distance "distance".
 
Write a solution to report the distance traveled by each user.
Return the result table ordered by travelled_distance in descending order, if two or more users traveled the same distance, order them by their name in ascending order.

 

https://leetcode.com/problems/top-travellers/description/?lang=pythondata

예시

Input: 
Users table:
+------+-----------+
| id   | name      |
+------+-----------+
| 1    | Alice     |
| 2    | Bob       |
| 3    | Alex      |
| 4    | Donald    |
| 7    | Lee       |
| 13   | Jonathan  |
| 19   | Elvis     |
+------+-----------+
Rides table:
+------+----------+----------+
| id   | user_id  | distance |
+------+----------+----------+
| 1    | 1        | 120      |
| 2    | 2        | 317      |
| 3    | 3        | 222      |
| 4    | 7        | 100      |
| 5    | 13       | 312      |
| 6    | 19       | 50       |
| 7    | 7        | 120      |
| 8    | 19       | 400      |
| 9    | 7        | 230      |
+------+----------+----------+
Output: 
+----------+--------------------+
| name     | travelled_distance |
+----------+--------------------+
| Elvis    | 450                |
| Lee      | 450                |
| Bob      | 317                |
| Jonathan | 312                |
| Alex     | 222                |
| Alice    | 120                |
| Donald   | 0                  |
+----------+--------------------+
Explanation: 
Elvis and Lee traveled 450 miles, Elvis is the top traveler as his name is alphabetically smaller than Lee.
Bob, Jonathan, Alex, and Alice have only one ride and we just order them by the total distances of the ride.
Donald did not have any rides, the distance traveled by him is 0.

문제 풀이

import pandas as pd

def top_travellers(users: pd.DataFrame, rides: pd.DataFrame) -> pd.DataFrame:
    # user별 총 주행 거리 계산
    total_distance  = rides.groupby('user_id')['distance'].sum().reset_index()
    
    # merge하여 user 정보와 총 주행 거리를 포함하는 df 생성
    merged = pd.merge(users, total_distance, left_on='id', right_on='user_id', how='left')[['name', 'distance']]
    
    # NaN을 0으로 대체하고 문제에서 제시한 기준대로 정렬
    result = merged.fillna(0).sort_values(by=['distance', 'name'], ascending=[False, True])
    
    result.rename(columns={'distance': 'travelled_distance'}, inplace=True)
    return result

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