Find longest calls

# Table: Contacts
# 
# +-------------+---------+
# | Column Name | Type    |
# +-------------+---------+
# | id          | int     |
# | first_name  | varchar |
# | last_name   | varchar |
# +-------------+---------+
# id is the primary key (column with unique values) of this table.
# id is a foreign key (reference column) to Calls table.
# Each row of this table contains id, first_name, and last_name.
# 
# Table: Calls
# 
# +-------------+------+
# | Column Name | Type |
# +-------------+------+
# | contact_id  | int  |
# | type        | enum |
# | duration    | int  |
# +-------------+------+
# (contact_id, type, duration) is the primary key (column with unique values) of this table.
# type is an ENUM (category) type of ('incoming', 'outgoing').
# Each row of this table contains information about calls, comprising of contact_id, type, and duration in seconds.
# 
# Write a solution to find the three longest incoming and outgoing calls.
# 
# Return the result table ordered by type, duration, and first_name in descending order and duration must be formatted as HH:MM:SS.
# 
# The result format is in the following example.
#
# Example 1:
# Input:
# Contacts table:
# +----+------------+-----------+
# | id | first_name | last_name |
# +----+------------+-----------+
# | 1  | John       | Doe       |
# | 2  | Jane       | Smith     |
# | 3  | Alice      | Johnson   |
# | 4  | Michael    | Brown     |
# | 5  | Emily      | Davis     |
# +----+------------+-----------+
# Calls table:
# +------------+----------+----------+
# | contact_id | type     | duration |
# +------------+----------+----------+
# | 1          | incoming | 120      |
# | 1          | outgoing | 180      |
# | 2          | incoming | 300      |
# | 2          | outgoing | 240      |
# | 3          | incoming | 150      |
# | 3          | outgoing | 360      |
# | 4          | incoming | 420      |
# | 4          | outgoing | 200      |
# | 5          | incoming | 180      |
# | 5          | outgoing | 280      |
# +------------+----------+----------+
# Output:
# +-----------+----------+-------------------+
# | first_name| type     | duration_formatted|
# +-----------+----------+-------------------+
# | Alice     | outgoing | 00:06:00          |
# | Emily     | outgoing | 00:04:40          |
# | Jane      | outgoing | 00:04:00          |
# | Michael   | incoming | 00:07:00          |
# | Jane      | incoming | 00:05:00          |
# | Emily     | incoming | 00:03:00          |
# +-----------+----------+-------------------+
# Explanation:
# Alice had an outgoing call lasting 6 minutes.
# Emily had an outgoing call lasting 4 minutes and 40 seconds.
# Jane had an outgoing call lasting 4 minutes.
# Michael had an incoming call lasting 7 minutes.
# Jane had an incoming call lasting 5 minutes.
# Emily had an incoming call lasting 3 minutes.
# Note: Output table is sorted by type, duration, and first_name in descending order.

import pandas as pd

def find_longest_calls(contacts: pd.DataFrame, calls: pd.DataFrame) -> pd.DataFrame:
  merged = calls.merge(contacts, left_on='contact_id', right_on='id')
  merged['rank'] = merged.groupby('type')['duration'].rank(method='dense', ascending=False)
  result = merged[merged['rank'] <= 3].copy()
  result['duration_formatted'] = result['duration'].apply(
    lambda s: f"{s // 3600:02d}:{(s % 3600) // 60:02d}:{s % 60:02d}"
  )
  result = result.sort_values(['type', 'duration', 'first_name'], ascending=[False, False, False])
  return result[['first_name', 'type', 'duration_formatted']].reset_index(drop=True)