CS @ ILLINOIS team tests problem-solving skills at ICPC 2017

The five hours students had to work at this year’s International Collegiate Programming Contest were winding down and the team from CS @ ILLINOIS had a problem.

Working in a cubicle alongside 127 other teams in an ice arena in Rapid City, South Dakota, the team had finished just two of a possible dozen problems and were stuck on one related to the “posterize” feature included in many photo-editing programs, team member Yewen Fan said.

“This actually is not a hard problem, but for some reason, all of us got stuck,” Fan said. “As more and more teams passed that problem, it became more stressful.”

So they divided up the work -- Fan bored in on the troubling problem, while his teammates, Yuting Zhang and Tong Li, moved on to another.

They solved both, giving the team four completed problems and a tie for 56th place in the Association for Computing Machinery’s worldwide competition. It was the best finish for a CS @ ILLINOIS team since 2009.

Some teams don’t solve any. The problems are intended to be fun, but also a real challenge:

How would you help a tiny, irregularly shaped island nation fit the longest possible runway across its limited land mass to jet in tourists? Or how would you assist your questionable friend Patrick as he tried to steal as many boxes of consumer widgets as possible and sneak them past a warehouse’s security system?

“Yuting and Tong did great -- they solved the fourth problem during the last hour, bringing us to the 56th place. We are happy about our performance,” Fan said.

The CS @ ILLINOIS team’s members brought complimentary skills to the competition, Zhang said.

“Yewen is very good at math problems. I am the fastest coder in the team and deal with most of the problems that require nontrivial implementations. Tong, on the other hand, often gives incisive observations on problems that are very difficult to approach,” Zhang said.

Team members were also at different points in their academic careers.

Li and Fan were both seniors at the time and have since graduated. Li is now working for Google while Fan is at Facebook. Zhang was a junior when the team went to Rapid City and will be a senior this fall.

The coaches, PhD students Uttam Thakore and Jingbo Shang, set up a schedule that put them through at least two practice competitions a week through the spring semester, starting with short sessions and gradually increasing the intensity to include sessions that mirrored what they’d face at the world finals.

Thakore and Shang are themselves experienced competitors.

Thakore competed twice at the regional level while at the University of Florida, and Shang competed as part of ICPC teams all four years as an undergrad at Shanghai Jiao Tong University. Shang says he would still be competing if the rules didn’t limit contestants to two finals appearances.

“I have exhausted my quota, but I'd like to deliver my knowledge and experience to newcomers,” he said.

But once the competition began, Thakore, Shang, and Teaching Professor Mattox Beckman - a coach who will take on a larger role in the coming year - were left on the sidelines with their counterparts from the other schools.

“It can be frustrating at times to watch time tick by without any submissions or solves … or even worse, seeing them rack up incorrect submission after incorrect submission,” Thakore said.

While there is a scoreboard, if things are going wrong, there’s no way to know why or exactly what’s happening, Thakore and Beckman said.

“With football you can see people running around getting clobbered. With coding, people are just there, at the computer typing away,” Beckman said.

Beckman and Shang will take over the team for the coming year. They believe the 2017 team built on an improving system for qualifying CS @ ILLINOIS teams for ICPC.

“We’re trying to move to a model where it’s like an actual sport -- you have to come to practices, we have tryouts,” Beckman said.

One thing he would like to improve: participation by women. The field was overwhelmingly male, he said.

Beckman hopes the experience can help sell itself, since he says it can be life-changing for students. That’s something Zhang agrees with.

“The whole team and coaches working together, friends and families supporting us. Everything adds up to make this event one of the most valuable experiences in my life,” he said.