리트코드 : 1393. Capital Gain/Loss

리트코드 : 1393. Capital Gain/Loss

• [link]

---

문제

Table: Stocks

+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| stock_name    | varchar |
| operation     | enum    |
| operation_day | int     |
| price         | int     |
+---------------+---------+
(stock_name, operation_day) is the primary key (combination of columns with unique values) for this table.
The operation column is an ENUM (category) of type ('Sell', 'Buy')
Each row of this table indicates that the stock which has stock_name had an operation on the day operation_day with the price.
It is guaranteed that each 'Sell' operation for a stock has a corresponding 'Buy' operation in a previous day. It is also guaranteed that each 'Buy' operation for a stock has a corresponding 'Sell' operation in an upcoming day.


Write a solution to report the Capital gain/loss for each stock.

The Capital gain/loss of a stock is the total gain or loss after buying and selling the stock one or many times.

Return the result table in any order.

The result format is in the following example.



Example 1:

Input: 
Stocks table:
+---------------+-----------+---------------+--------+
| stock_name    | operation | operation_day | price  |
+---------------+-----------+---------------+--------+
| Leetcode      | Buy       | 1             | 1000   |
| Corona Masks  | Buy       | 2             | 10     |
| Leetcode      | Sell      | 5             | 9000   |
| Handbags      | Buy       | 17            | 30000  |
| Corona Masks  | Sell      | 3             | 1010   |
| Corona Masks  | Buy       | 4             | 1000   |
| Corona Masks  | Sell      | 5             | 500    |
| Corona Masks  | Buy       | 6             | 1000   |
| Handbags      | Sell      | 29            | 7000   |
| Corona Masks  | Sell      | 10            | 10000  |
+---------------+-----------+---------------+--------+
Output: 
+---------------+-------------------+
| stock_name    | capital_gain_loss |
+---------------+-------------------+
| Corona Masks  | 9500              |
| Leetcode      | 8000              |
| Handbags      | -23000            |
+---------------+-------------------+
Explanation: 
Leetcode stock was bought at day 1 for 1000$ and was sold at day 5 for 9000$. Capital gain = 9000 - 1000 = 8000$.
Handbags stock was bought at day 17 for 30000$ and was sold at day 29 for 7000$. Capital loss = 7000 - 30000 = -23000$.
Corona Masks stock was bought at day 1 for 10$ and was sold at day 3 for 1010$. It was bought again at day 4 for 1000$ and was sold at day 5 for 500$. At last, it was bought at day 6 for 1000$ and was sold at day 10 for 10000$. Capital gain/loss is the sum of capital gains/losses for each ('Buy' --> 'Sell') operation = (1010 - 10) + (500 - 1000) + (10000 - 1000) = 1000 - 500 + 9000 = 9500$.

• 각 주식별 총 gain loss 구하기

 

문제 풀이

MySQL

select stock_name, sum(if(operation='buy', -price, price)) as capital_gain_loss
from stocks
group by stock_name

• 처음에는 group by로 주식별 buy sell 나누려고 했다.
• 이러면 두 테이블 join시 null값을 처리해야해서 한 번에 sum if로 처리
• 1등 코드랑 거의 똑같이 짰음~

Pandas

import pandas as pd

def capital_gainloss(stocks: pd.DataFrame) -> pd.DataFrame:
    stocks['capital_gain_loss']=np.where(stocks['operation']=='Buy', -stocks['price'],stocks['price'])
    return stocks.groupby('stock_name')['capital_gain_loss'].sum().reset_index()

• 같은 방식으로 짠 코드.
• sum if 대신 np.where로 조건걸어주기.

 

코멘트

• 개인 레퍼런스 만들면서 보는중인데, 생각나는 부분은 확실히 빨라졌다.