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Your Instructors

Geoffrey Challen is the primary creator and maintainer of learncs.online.

Geoffrey authored the lesson content and homework problems, and created and maintains the backend systems that power the playgrounds, explanations, problems, and other interactive website content. You can find more details about the course infrastructure and more complete credits here.

However, in the years since the original materials were created, other students and faculty from the University of Illinois, students from other institutions, and learncs.online students have contributed to the learncs.online materials. All contributors are listed below, starting with verified instructors.

If you'd like to contribute, please get in touch!

Instructors

Geoffrey Challen
Geoffrey Challen
he, him, his
Kotlin
Java
924 contributions
Colleen Lewis
Colleen Lewis
 
Kotlin
Java
326 contributions
Ellen Spertus
Ellen Spertus
she, her, hers
Teaching Professor, Khoury College of Computer Sciences, Northeastern University
Kotlin
Java
44 contributions
Chris Taylor
Chris Taylor
he, him, his
Java
36 contributions

Teacher

Rohith Sanjay
Rohith Sanjay
 
Kotlin
Java
115 contributions
Carlos Inigo Fernandez
Carlos Inigo Fernandez
 
Java
41 contributions
Conor Cunningham
Conor Cunningham
 
Java
37 contributions
Thomas Cai
Thomas Cai
 
Kotlin
Java
34 contributions
Miguel Fernandez
Miguel Fernandez
 
Kotlin
Java
30 contributions
Jackie Chan
Jackie Chan
 
Kotlin
Java
28 contributions

Tutor

Rachanon Petchoo
Rachanon Petchoo
 
Java
22 contributions
Arnav Sethi
Arnav Sethi
 
Java
21 contributions
Haosen Yao
Haosen Yao
 
Kotlin
Java
21 contributions
Carl Edwards
Carl Edwards
 
Java
21 contributions
Benjamin Chang
Benjamin Chang
 
Kotlin
19 contributions
Jacob Chang
Jacob Chang
 
Kotlin
Java
19 contributions
Patrick Cunningham
Patrick Cunningham
 
Java
18 contributions
Ritvik Sood
Ritvik Sood
 
Java
18 contributions
Aden Krakman
Aden Krakman
 
Java
17 contributions
Ying Chen
Ying Chen
 
Java
17 contributions
Justin Bai
Justin Bai
 
Kotlin
17 contributions
Rohan Gudipaty
Rohan Gudipaty
 
Java
16 contributions
Hyunho Kim
Hyunho Kim
 
Kotlin
Java
16 contributions

Assistant

Sam Erens
Sam Erens
 
Kotlin
Java
15 contributions
Nancy Jia
Nancy Jia
 
Kotlin
Java
13 contributions
Tom Sui
Tom Sui
 
Java
13 contributions
Alistair Forsyth
Alistair Forsyth
 
Kotlin
13 contributions
Yuxuan Chen
Yuxuan Chen
 
Java
12 contributions
Ruisong Li
Ruisong Li
 
Kotlin
Java
12 contributions
Kaan Yigit
Kaan Yigit
 
Java
12 contributions
Michael Rheintgen
Michael Rheintgen
 
Kotlin
12 contributions
Boyang Sun
Boyang Sun
 
Java
11 contributions
Matt Twyman
Matt Twyman
 
Java
11 contributions
Maxwell Yang
Maxwell Yang
 
Java
11 contributions
Elijah Mock
Elijah Mock
 
Kotlin
Java
11 contributions
Jay Chen
Jay Chen
 
Java
11 contributions
Collin Fox
Collin Fox
 
Java
10 contributions
Zijing Wei
Zijing Wei
 
Kotlin
Java
10 contributions
Zuhair Ali
Zuhair Ali
 
Kotlin
Java
10 contributions
Kevin Liu
Kevin Liu
 
Java
10 contributions
Zainab Memon
Zainab Memon
 
Java
10 contributions
Saashin Subramaniam
Saashin Subramaniam
 
Java
10 contributions
Sriya Mikkilineni
Sriya Mikkilineni
 
Java
9 contributions
Ben Clarage
Ben Clarage
 
Kotlin
Java
9 contributions
Niharika Bhattacharjee
Niharika Bhattacharjee
 
Java
9 contributions
Carolyn Zeng
Carolyn Zeng
 
Kotlin
Java
9 contributions
Prith Balaji
Prith Balaji
 
Java
9 contributions
Jake Cumberland
Jake Cumberland
 
Java
9 contributions
Christopher Sahyouni
Christopher Sahyouni
 
Java
9 contributions
Cristian Flores
Cristian Flores
 
Java
8 contributions
Arghya Srivastav
Arghya Srivastav
 
Java
8 contributions
Anushree Tibrewal
Anushree Tibrewal
 
Java
8 contributions
Nathaniel Zukowski
Nathaniel Zukowski
 
Java
8 contributions
Anagha Shenoy
Anagha Shenoy
 
Kotlin
8 contributions
Daniel Gutierrez
Daniel Gutierrez
 
Java
8 contributions
Rohan Shah
Rohan Shah
 
Kotlin
8 contributions
Jason Cai
Jason Cai
 
Kotlin
Java
8 contributions
Sunwoo Baek
Sunwoo Baek
 
Java
8 contributions
Maaheen Maajed
Maaheen Maajed
 
Kotlin
Java
7 contributions
Lexi Ippolito
Lexi Ippolito
 
Java
7 contributions
Adelia Solarman
Adelia Solarman
 
Java
7 contributions
Alex Gong
Alex Gong
 
Java
7 contributions
Meera Jagannathan
Meera Jagannathan
 
Java
7 contributions
Hrishikesh Kalyanaraman
Hrishikesh Kalyanaraman
 
Java
7 contributions
Justin Kim
Justin Kim
 
Kotlin
Java
7 contributions
Brendan Biernacki
Brendan Biernacki
 
Java
7 contributions
Daniel Song
Daniel Song
 
Kotlin
Java
7 contributions
Chris Whamond
Chris Whamond
 
Kotlin
Java
7 contributions
Kaiwen Mo
Kaiwen Mo
 
Java
7 contributions
Anirudh Kumar
Anirudh Kumar
 
Java
6 contributions
Grace Jia
Grace Jia
 
Kotlin
Java
6 contributions
Diego Taveras
Diego Taveras
 
Kotlin
6 contributions
Ishika Awachat
Ishika Awachat
 
Java
6 contributions
Zhuoang Tao
Zhuoang Tao
 
Kotlin
Java
6 contributions
Prem Dhoot
Prem Dhoot
 
Java
6 contributions
Eugene Jang
Eugene Jang
 
Java
6 contributions
Anakin Dey
Anakin Dey
 
Java
6 contributions
Saagar Kolachina
Saagar Kolachina
 
Kotlin
Java
6 contributions
Ahmed Hasan
Ahmed Hasan
 
Kotlin
Java
6 contributions
Amirthavarshini Sureshbabu
Amirthavarshini Sureshbabu
 
Java
6 contributions
Henry Tang
Henry Tang
 
Java
6 contributions
Arpit Bansal
Arpit Bansal
 
Kotlin
Java
6 contributions

Helper

Jonathan You
Jonathan You
 
Java
5 contributions
Delu Zhao
Delu Zhao
 
Java
5 contributions
Monica Para
Monica Para
 
Kotlin
Java
5 contributions
Amaan Mirza
Amaan Mirza
 
Java
5 contributions
Mike Cheng
Mike Cheng
 
Kotlin
5 contributions
Harsh Deep
Harsh Deep
 
Java
5 contributions
Arjun Prabhu
Arjun Prabhu
 
Java
5 contributions
Zhilan Wang
Zhilan Wang
 
Java
5 contributions
Sarah O'Sullivan
Sarah O'Sullivan
 
Java
5 contributions
Raul Higareda
Raul Higareda
 
Java
5 contributions
Utkarsh Prasad
Utkarsh Prasad
 
Java
5 contributions
Aashi Tyagi
Aashi Tyagi
 
Java
5 contributions
Chinonso Chinonso
Chinonso Chinonso
 
Kotlin
5 contributions
Jongwoo Jeon
Jongwoo Jeon
 
Java
4 contributions
Anuprova Bhowmik
Anuprova Bhowmik
 
Kotlin
Java
4 contributions
Matt Yang
Matt Yang
 
Java
4 contributions
Youngmin Jeon
Youngmin Jeon
 
Java
4 contributions
Leo Li
Leo Li
 
Java
4 contributions
Akul Gupta
Akul Gupta
 
Java
4 contributions
Freddy Platinus
Freddy Platinus
 
Java
4 contributions
Gargi Balasubramaniam
Gargi Balasubramaniam
 
Java
4 contributions
Samuel Schapiro
Samuel Schapiro
 
Java
4 contributions
Charlie Rivera
Charlie Rivera
 
Java
4 contributions
Arnav Motwani
Arnav Motwani
 
Kotlin
4 contributions
Ashley Wang
Ashley Wang
 
Java
4 contributions
Daniyal Rana
Daniyal Rana
 
Java
4 contributions
Leena Abdelrahman
Leena Abdelrahman
 
Java
4 contributions
Rahul Kalle
Rahul Kalle
 
Java
4 contributions
Rylan Turner
Rylan Turner
 
Java
4 contributions
Larry Liao
Larry Liao
 
Java
4 contributions
Zetai Liu
Zetai Liu
 
Java
4 contributions
Aditya Joshi
Aditya Joshi
 
Java
4 contributions
Prerana Singh
Prerana Singh
she, her, hers
Java
4 contributions
Hania Dziurdzik
Hania Dziurdzik
 
Kotlin
Java
4 contributions
Dj Figueiredo
Dj Figueiredo
 
Kotlin
4 contributions
Yiming Niu
Yiming Niu
 
Java
4 contributions
Haozhe Li
Haozhe Li
 
Java
4 contributions
Milosz Dabrowski
Milosz Dabrowski
 
Java
3 contributions
James Rockey
James Rockey
 
Java
3 contributions
Ojas Upalekar
Ojas Upalekar
 
Java
3 contributions
Bernie Zhu
Bernie Zhu
 
Java
3 contributions
Jane Liu
Jane Liu
 
Java
3 contributions
Rachel Huang
Rachel Huang
 
Java
3 contributions
Ayaan Jabbar
Ayaan Jabbar
 
Kotlin
3 contributions
Neel Khare
Neel Khare
 
Java
3 contributions
Violetta Dabros
Violetta Dabros
 
Java
3 contributions
Palak Purwar
Palak Purwar
 
Java
3 contributions
Samarth Taneja
Samarth Taneja
 
Java
3 contributions
Serena Trika
Serena Trika
 
Java
3 contributions
Yuhua Weng
Yuhua Weng
 
Java
3 contributions
Anish Meka
Anish Meka
 
Java
3 contributions
Apramey Hosahalli
Apramey Hosahalli
 
Java
3 contributions
Aarav Mande
Aarav Mande
 
Java
3 contributions
Idrees Mohammed
Idrees Mohammed
 
Kotlin
Java
3 contributions
Daniel Rugutt
Daniel Rugutt
 
Java
3 contributions
Eduardo Martinez
Eduardo Martinez
 
Java
3 contributions
Lina Mei
Lina Mei
 
Kotlin
3 contributions
Serlina Ku
Serlina Ku
 
Java
3 contributions
Sana Madhavan
Sana Madhavan
 
Java
3 contributions
Alyssa Daniels
Alyssa Daniels
 
Java
3 contributions
Preston Chao
Preston Chao
 
Java
3 contributions
Warren Li
Warren Li
 
Java
3 contributions
Ananya Subramanian
Ananya Subramanian
 
Java
3 contributions
Kushal Agarwal
Kushal Agarwal
 
Java
3 contributions
Zhaoyang Chen
Zhaoyang Chen
 
Kotlin
3 contributions
Yu He
Yu He
 
Java
3 contributions
David Ruvinskiy
David Ruvinskiy
 
Kotlin
3 contributions
Aditi Khanna
Aditi Khanna
 
Java
3 contributions
Archna Sobti
Archna Sobti
 
Java
3 contributions
Savannah Holly
Savannah Holly
 
Java
3 contributions
Anish Thiriveedhi
Anish Thiriveedhi
 
Java
3 contributions
Joy Wan
Joy Wan
 
Java
3 contributions
Jainil Modi
Jainil Modi
 
Java
3 contributions
Vansh Sikka
Vansh Sikka
 
Java
3 contributions
Vansh Gupta
Vansh Gupta
 
Java
3 contributions
Will Otani
Will Otani
 
Java
3 contributions
Havish Rani
Havish Rani
 
Java
3 contributions
Lenna Park
Lenna Park
 
Java
3 contributions
Ananyaa Tanwar
Ananyaa Tanwar
 
Java
3 contributions
Meghna Mavila
Meghna Mavila
 
Java
3 contributions
Josh Joseph
Josh Joseph
 
Java
3 contributions
Wendy Ruan
Wendy Ruan
 
Java
3 contributions
Nishit Samarth
Nishit Samarth
 
Java
3 contributions
Chengze Shen
Chengze Shen
 
Java
3 contributions
Becky Blake
Becky Blake
 
Java
3 contributions
Gabriel Grais
Gabriel Grais
 
Java
3 contributions
Juyoung Choi
Juyoung Choi
 
Java
3 contributions
Qingping Ye
Qingping Ye
 
Java
3 contributions
Kavin Krishnasami
Kavin Krishnasami
 
Java
3 contributions
Helen Ilkiu
Helen Ilkiu
 
Java
3 contributions
Athena Fung
Athena Fung
 
Java
3 contributions
Tyler Cushing
Tyler Cushing
 
Kotlin
3 contributions
David Yang
David Yang
 
Java
3 contributions
Di Liang
Di Liang
 
Java
3 contributions
Andrew Kim
Andrew Kim
 
Kotlin
3 contributions
Eric Ji
Eric Ji
 
Java
3 contributions
Chris Munoz
Chris Munoz
 
Java
3 contributions
Joseph Dubravec
Joseph Dubravec
 
Java
3 contributions
Meghna Gaddam
Meghna Gaddam
 
Java
3 contributions
Martina Perez Zuleta
Martina Perez Zuleta
 
Java
3 contributions
Andrew Lum
Andrew Lum
 
Java
3 contributions
Jenny Yang
Jenny Yang
 
Java
3 contributions
Eunice Leung
Eunice Leung
 
Java
3 contributions
Tianyun Zhang
Tianyun Zhang
 
Java
3 contributions
Elisa Carrillo
Elisa Carrillo
 
Java
3 contributions
Louis Qian
Louis Qian
 
Java
3 contributions
Ishq Gupta
Ishq Gupta
 
Java
3 contributions
Jier Miao
Jier Miao
 
Java
3 contributions
Elijah Song
Elijah Song
 
Kotlin
3 contributions
Bilal Karim
Bilal Karim
 
Java
3 contributions
Junhao Xiong
Junhao Xiong
 
Java
3 contributions
Mick Enev
Mick Enev
 
Java
3 contributions
Matthew McCarthy
Matthew McCarthy
 
Kotlin
3 contributions
Lexi Guan
Lexi Guan
 
Java
3 contributions
Ethan Sirois
Ethan Sirois
 
Kotlin
3 contributions
Alekhya Nathella
Alekhya Nathella
 
Java
2 contributions
Harshit Bagla
Harshit Bagla
 
Java
2 contributions
Daniel Dilan
Daniel Dilan
 
Java
2 contributions
Sarod Nori
Sarod Nori
 
Java
2 contributions
Samuel Hurh
Samuel Hurh
 
Java
2 contributions
Ayah Jaber
Ayah Jaber
 
Java
2 contributions
Adrian Russo
Adrian Russo
 
Java
2 contributions
Shao-Min Yeh
Shao-Min Yeh
 
Java
2 contributions
Janani Jayanth
Janani Jayanth
 
Java
2 contributions
Rohan Sathe
Rohan Sathe
 
Java
2 contributions
Alex Che
Alex Che
 
Java
2 contributions
Jake Vile
Jake Vile
 
Java
2 contributions
Tanay Pareek
Tanay Pareek
 
Java
2 contributions
Kangyu Feng
Kangyu Feng
 
Java
2 contributions
Ken Kim
Ken Kim
 
Java
2 contributions
Brandon Dinh
Brandon Dinh
 
Java
2 contributions
Ishan Khandelwal
Ishan Khandelwal
 
Java
2 contributions
Tina Dou
Tina Dou
 
Java
2 contributions
Emmanuel Buabeng
Emmanuel Buabeng
 
Java
2 contributions
Yiche Liu
Yiche Liu
 
Java
2 contributions
Alma Zirojevic
Alma Zirojevic
 
Java
2 contributions
Anna Fedczuk
Anna Fedczuk
 
Java
2 contributions
Armin Rafieyan
Armin Rafieyan
 
Kotlin
2 contributions
Anna Liu
Anna Liu
 
Java
2 contributions
Vaibhav Keshari
Vaibhav Keshari
 
Kotlin
2 contributions
Allen Guo
Allen Guo
 
Java
2 contributions
Rahul Bhatt
Rahul Bhatt
 
Java
2 contributions
Brenda Hariyanto
Brenda Hariyanto
 
Java
2 contributions
Abhi Vinnakota
Abhi Vinnakota
 
Java
2 contributions
Ruozhen Yang
Ruozhen Yang
 
Java
2 contributions
Edmon Guan
Edmon Guan
 
Java
2 contributions
Sabrina Tu
Sabrina Tu
 
Java
2 contributions
Joseph Chan
Joseph Chan
 
Java
2 contributions
Dawn Lim
Dawn Lim
 
Kotlin
2 contributions
Yasmine Munoz
Yasmine Munoz
 
Java
2 contributions
Tianyi Huang
Tianyi Huang
 
Java
2 contributions
Cloud Li
Cloud Li
 
Java
2 contributions
Zoe Lu
Zoe Lu
 
Java
2 contributions
Srikar Manikonda
Srikar Manikonda
 
Java
2 contributions
Yuan Ochoa
Yuan Ochoa
 
Java
2 contributions
Yanze Lu
Yanze Lu
 
Java
2 contributions
Vish Ganesan
Vish Ganesan
 
Kotlin
2 contributions
Kelly Chen
Kelly Chen
 
Java
2 contributions
Grace Cho
Grace Cho
 
Java
2 contributions
Jared Buabeng
Jared Buabeng
 
Java
2 contributions
Nathan Liu
Nathan Liu
 
Java
2 contributions
Manasi Vaidya
Manasi Vaidya
 
Java
2 contributions
Max Jing
Max Jing
 
Kotlin
Java
2 contributions
Elizabeth Spencer
Elizabeth Spencer
 
Kotlin
2 contributions
Steven Salisbury
Steven Salisbury
 
Kotlin
2 contributions
Lou Zeh
Lou Zeh
 
Java
1 contribution
Juan David Campolargo Hoyos
Juan David Campolargo Hoyos
 
Java
1 contribution
Ethan Miranda
Ethan Miranda
 
Kotlin
1 contribution
Mayank Hirani
Mayank Hirani
 
Java
1 contribution
Aditya Shreenivas Kunte
Aditya Shreenivas Kunte
 
Java
1 contribution
Siddharth Tangri
Siddharth Tangri
 
Java
1 contribution
Vinayak Manepalli
Vinayak Manepalli
 
Java
1 contribution
Varun Shroff
Varun Shroff
 
Java
1 contribution
Rohan Khatu
Rohan Khatu
 
Java
1 contribution
Adrian Rodriguez
Adrian Rodriguez
 
Java
1 contribution
Tongyun Huang
Tongyun Huang
 
Java
1 contribution
Shruthi Jaganathan
Shruthi Jaganathan
 
Java
1 contribution
Nicholas Jung
Nicholas Jung
 
Java
1 contribution
Dazhen Chen
Dazhen Chen
 
Java
1 contribution
Cindy Su
Cindy Su
 
Java
1 contribution
Jason Wu
Jason Wu
 
Java
1 contribution
Ricky Chen
Ricky Chen
 
Java
1 contribution
Jason Barnett
Jason Barnett
 
Kotlin
1 contribution
Anish Jampana
Anish Jampana
 
Java
1 contribution
Siyuan Ding
Siyuan Ding
 
Java
1 contribution
Aadarsh Krishnan
Aadarsh Krishnan
 
Java
1 contribution
Matthew Czech
Matthew Czech
 
Java
1 contribution
Raghav Anand
Raghav Anand
 
Java
1 contribution
Edward Huang
Edward Huang
 
Java
1 contribution
Meghan Lu
Meghan Lu
 
Java
1 contribution
Jimmy Berg
Jimmy Berg
 
Kotlin
1 contribution
Aryan Vakharia
Aryan Vakharia
 
Java
1 contribution
Connor Flynn
Connor Flynn
 
Java
1 contribution
Aaron Taub
Aaron Taub
 
Java
1 contribution
Nehal Tangudu
Nehal Tangudu
 
Java
1 contribution
Anisha Raja
Anisha Raja
 
Java
1 contribution
Thomas Zelichowski
Thomas Zelichowski
 
Java
1 contribution
Saurav Chittal
Saurav Chittal
 
Java
1 contribution
Blair Wang
Blair Wang
 
Java
1 contribution
Keshav Trikha
Keshav Trikha
 
Java
1 contribution
Jessica Ho
Jessica Ho
 
Java
1 contribution
Hamiz Anjum
Hamiz Anjum
 
Java
1 contribution
Simon Li
Simon Li
 
Java
1 contribution
Ziyin Wang
Ziyin Wang
 
Java
1 contribution
Ram Goenka
Ram Goenka
 
Java
1 contribution
Ryan Wang
Ryan Wang
 
Kotlin
1 contribution
Shoorsen Gandhi
Shoorsen Gandhi
 
Kotlin
1 contribution
Joe Tamulaitis
Joe Tamulaitis
 
Kotlin
1 contribution
Tracy Li
Tracy Li
 
Kotlin
1 contribution
Panyue Chen
Panyue Chen
 
Java
1 contribution
Jiaqi He
Jiaqi He
 
Java
1 contribution
Punn Pinkayan
Punn Pinkayan
 
Java
1 contribution
Wentao Qi
Wentao Qi
 
Java
1 contribution
Ishaan Bhandari
Ishaan Bhandari
 
Java
1 contribution

Student Contributors

The following students have contributed explanations to learncs.online, which have been approved by instructors and now appear on the website:

Jorge R.
Jorge R.
 
Java
4 contributions
Ayesha Ahmed
Ayesha Ahmed
 
Java
1 contribution
Jo Ma Me
Jo Ma Me
 
Java
1 contribution
Sisa Pallchisaca
Sisa Pallchisaca
 
Java
1 contribution
Nathan Chen
Nathan Chen
 
Kotlin
1 contribution
Chinasa Nwosu
Chinasa Nwosu
 
Java
1 contribution
Michal Lampejo
Michal Lampejo
 
Java
1 contribution
Aisha Salau
Aisha Salau
 
Java
1 contribution
KJ _Sodipe
KJ _Sodipe
 
Java
1 contribution
Daniel Lopez
Daniel Lopez
 
Java
1 contribution
Chris Perfecto
Chris Perfecto
 
Kotlin
1 contribution
Valeria Horta
Valeria Horta
 
Java
1 contribution

Question Authors

Questions on the lessons and practice page were authored by the following contributors:

Geoffrey Challen
Geoffrey Challen
 
Kotlin
Java
396 questions
(376 Kotlin, 396 Java)
Chris Taylor
Chris Taylor
 
Kotlin
Java
36 questions
(2 Kotlin, 36 Java)
Ellen Spertus
Ellen Spertus
 
Java
14 questions
(0 Kotlin, 14 Java)
Miguel Fernandez
Miguel Fernandez
 
Kotlin
Java
2 questions
(2 Kotlin, 2 Java)
Harsh Deep
Harsh Deep
 
Kotlin
Java
1 question
(1 Kotlin, 1 Java)
Ayesha Ahmed
Ayesha Ahmed
 
Kotlin
Java
1 question
(1 Kotlin, 1 Java)
CEO
CEO
 
Kotlin
Java
1 question
(1 Kotlin, 1 Java)
Michal Lampejo
Michal Lampejo
 
Kotlin
Java
1 question
(1 Kotlin, 1 Java)
Giovanni Pastor
Giovanni Pastor
 
Kotlin
Java
1 question
(1 Kotlin, 1 Java)
Aisha Salau
Aisha Salau
 
Kotlin
Java
1 question
(1 Kotlin, 1 Java)
Nikita Neledov
Nikita Neledov
 
Kotlin
Java
1 question
(1 Kotlin, 1 Java)