Consecutive Numbers — LeetCode 180 Python Solution

The problem

Find every number that appears three or more times in a row when the log is read in id order. The Logs table has id (int, primary key, autoincrementing from 1) and num (varchar). Report each qualifying number once, in a column named ConsecutiveNums.

Example

Input

Logs(id, num) = (1, '5'), (2, '5'), (3, '5'), (4, '7'), (5, '7'), (6, '5'), (7, '5')

Output

ConsecutiveNums = 5

Explanation

5 occupies ids 1, 2 and 3 — three consecutive rows — while 7 never runs longer than two.

Python solution

import pandas as pd


def consecutive_numbers(logs: pd.DataFrame) -> pd.DataFrame:
    all_the_same = lambda lst: lst.nunique() == 1
    logs["is_consecutive"] = (
        logs["num"].rolling(window=3, center=True, min_periods=3).apply(all_the_same)
    )
    return (
        logs.query("is_consecutive == 1.0")[["num"]]
        .drop_duplicates()
        .rename(columns={"num": "ConsecutiveNums"})
    )

Complexity

Related problems