Human Traffic of Stadium — LeetCode 601 Python Solution

The problem

Report the rows that belong to a stretch of three or more consecutive ids in which every day drew at least 100 visitors, ordered by visit date. The Stadium table has one row per day: id (int), visit_date (date, the column with unique values) and people (int, the number of visitors that day). The id grows together with the date.

Example

Stadium table:

| id | visit_date | people |
| -- | ---------- | ------ |
| 1  | 2024-07-01 | 145    |
| 2  | 2024-07-02 | 80     |
| 3  | 2024-07-03 | 210    |
| 4  | 2024-07-04 | 190    |
| 5  | 2024-07-05 | 155    |
| 6  | 2024-07-06 | 95     |

Result:

| id | visit_date | people |
| -- | ---------- | ------ |
| 3  | 2024-07-03 | 210    |
| 4  | 2024-07-04 | 190    |
| 5  | 2024-07-05 | 155    |

Ids 3, 4 and 5 form a run of three busy days; id 1 is busy but isolated, and ids 2 and 6 fall under 100.

Python solution

import pandas as pd

def human_traffic(stadium: pd.DataFrame) -> pd.DataFrame:
    df = stadium[stadium['people'] >= 100].sort_values('id')
    df['grp'] = (df['id'].diff() != 1).cumsum()
    sizes = df.groupby('grp')['id'].transform('count')
    res = df[sizes >= 3][['id', 'visit_date', 'people']]
    return res.sort_values('id')

Complexity

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