How hard is LeetCode 1731. The Number of Employees Which Report to Each Employee?

LeetCode 1731. The Number of Employees Which Report to Each Employee is rated Easy on LeetCode.

What topics does LeetCode 1731. The Number of Employees Which Report to Each Employee cover?

LeetCode 1731. The Number of Employees Which Report to Each Employee is tagged Database on LeetCode.

EasyNo. 1731

The Number of Employees Which Report to Each Employee — LeetCode 1731 Python Solution

Topics: Database
Reading time: 3 min
Source: leetcode.com

Table schema

SQLTable schema

Table: Employees +-------------+----------+ | Column Name | Type | +-------------+----------+ | employee_id | int | | name | varchar | | reports_to | int | | age | int | +-------------+----------+ employee_id is the column with unique values for this table. This table contains information about the employees and the id of the manager they report to.

Example

SQLExample

+-------------+----------+
| Column Name | Type     |
+-------------+----------+
| employee_id | int      |
| name        | varchar  |
| reports_to  | int      |
| age         | int      |
+-------------+----------+
employee_id is the column with unique values for this table.
This table contains information about the employees and the id of the manager they report to. Some employees do not report to anyone (reports_to is null).

Python solution

PythonSolution

import duckdb
import pandas as pd

def solution(employees: pd.DataFrame) -> pd.DataFrame:
    con = duckdb.connect()
    con.register("Employees", employees)
    return con.execute("""SELECT
    e2.employee_id,
    e2.name,
    COUNT(1) AS reports_count,
    ROUND(AVG(e1.age)) AS average_age
FROM
    Employees AS e1
    JOIN Employees AS e2 ON e1.reports_to = e2.employee_id
GROUP BY 1
ORDER BY 1;""").df()

Complexity

Time: O(n log n)(typical)
Space · auxiliary: O(n)

Related problems
No.	Problem	Difficulty
0175	Combine Two Tables	Easy
0176	Second Highest Salary	Medium
0177	Nth Highest Salary	Medium
0178	Rank Scores	Medium
0180	Consecutive Numbers	Medium
0181	Employees Earning More Than Their Managers	Easy

Frequently asked questions

How hard is LeetCode 1731. The Number of Employees Which Report to Each Employee?: LeetCode 1731. The Number of Employees Which Report to Each Employee is rated Easy on LeetCode.
What topics does LeetCode 1731. The Number of Employees Which Report to Each Employee cover?: LeetCode 1731. The Number of Employees Which Report to Each Employee is tagged Database on LeetCode.

Stuck on problems like this in a live interview?

Stealth Interview is a desktop app for macOS and Windows. It reads the problem off your screen and returns a working solution with a step-by-step explanation and its time and space complexity, invisible to screen sharing.

Download for Mac Download for Windows

Free to download. Check it runs on your machine, then pick a plan.

90%Subscription

python

Please analyze this context and help me answer the question or solve the problem.

Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

Technical interview · 45 minsolution.pyShared editor · Python 3Longest substring without repeatsMediumGiven a string s, return the length of the longest contiguous substring in which every character is unique.s = "abcabcbb"
→ 31def length_of_longest_substring(s: str) -> int:2 last_seen = {}3 left = best = 04 for right, ch in enumerate(s):5 if ch in last_seen and last_seen[ch] >= left:

python

def length_of_longest_substring(s: str) -> int:    last_seen = {}                    # char -> index    left = best = 0    for right, ch in enumerate(s):        if ch in last_seen and last_seen[ch] >= left:            left = last_seen[ch] + 1  # jump past it        last_seen[ch] = right        best = max(best, right - left + 1)    return best    last_seen = {}                    # char -> index

Approach

At each index r, the window's left edge is:

left r = max (left r -1, last[s r] + 1)

Time O(n): each character enters and leaves the window once.
Space O(min(n, k)): k is the size of the character set.

Type your message...

GPT-6.1 Terra

Transcribing...

90%Subscription

python

Please analyze this context and help me answer the question or solve the problem.

Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

python

def length_of_longest_substring(s: str) -> int:    last_seen = {}                    # char -> index    left = best = 0    for right, ch in enumerate(s):        if ch in last_seen and last_seen[ch] >= left:            left = last_seen[ch] + 1  # jump past it        last_seen[ch] = right        best = max(best, right - left + 1)    return best    last_seen = {}                    # char -> index

Approach

At each index r, the window's left edge is:

left r = max (left r -1, last[s r] + 1)

Time O(n): each character enters and leaves the window once.
Space O(min(n, k)): k is the size of the character set.

Type your message...

GPT-6.1 TerraClear chat

Transcribing...

QuitEscHide+QCapture+PCrop+OSubmit+EnterPress to get answerLeft/Right+Up/Down+

90%Subscription

python

Please analyze this context and help me answer the question or solve the problem.

Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

python

def length_of_longest_substring(s: str) -> int:    last_seen = {}                    # char -> index    left = best = 0    for right, ch in enumerate(s):        if ch in last_seen and last_seen[ch] >= left:            left = last_seen[ch] + 1  # jump past it        last_seen[ch] = right        best = max(best, right - left + 1)    return best    last_seen = {}                    # char -> index

Approach

At each index r, the window's left edge is:

left r = max (left r -1, last[s r] + 1)

Time O(n): each character enters and leaves the window once.
Space O(min(n, k)): k is the size of the character set.

Type your message...

GPT-6.1 TerraClear chat

Transcribing...

Primary display

QuitEscHide+QCapture+PCrop+OSubmit+EnterPress to get answerLeft/Right+Up/Down+

Table schema

Example

Python solution

Complexity

Related problems

Frequently asked questions

Stuck on problems like this in a live interview?

Approach

Approach

Approach