Lounging on the lawn of California Memorial Stadium on Sunday, three UC Berkeley hackers chewed on pizza, rested from 36 consecutive hours of work and deliberated on the definition of hacking.

“Unlocking the potential of anything,” said UC Berkeley sophomore Carlos Sanchez.

“Half reinventing, half problem-solving,” said sophomore Robert Norte.

“Companies bribe you with a bunch of technology and see what you can do with it,” said sophomore Jacqueline Liu.

What these hackers did all weekend was not malicious or illegal — they were tinkering with technology. They were joined by more than 1,000 other participants from schools across North America, filling the club space within the stadium for a hackathon that lasted for a day and a half.

The hackers were challenged to build hardware and software for a prize pool of $2,000 in addition to sponsor contributions, totaling more than $5,000. Projects were judged by a panel of two campus professors and industry experts from companies including Microsoft, Aerospike and Quixey.

Cal Hacks is part of Major League Hacking, an organization that puts on more than 50 hackathons across North America and the United Kingdom each semester.

Although Cal Hacks is not the first hackathon in the Bay Area, “it’s definitely the most well branded,” said Justin Brezhnev, coaching program director at MLH. The proximity to Silicon Valley makes Cal Hacks an important target for tech companies, Brezhnev added.

Hackers attended an opening ceremony with speeches from industry leaders Friday evening before hacking began at midnight. The finished products, from a car controlled by brainwaves to an app for delivering packages with Uber, were turned in for judging at noon Sunday.

The top prize went to MindDrone, a team of three UC Berkeley students, one student from Pierce College and one from Duke University who built a flying drone maneuvered by neurological signals.

“We wanted to show the world that BCI (brain-computer interface) is not something in the future — it’s in the present,” said Tomas Vega, a UC Berkeley student and member of the winning team.

Representatives of companies such as Dropbox, Uber and Facebook tabled on the second floor of the stadium and encouraged participants to take breaks with panels and workshops.

“Entrepreneurs are getting younger and younger — they’re making really cool things and working on amazing technologies out there,” said Justin Sayarath, who graduated from UC Berkeley in 2013 and now represents Kleiner Perkins Caufield & Byers, a Silicon Valley venture capital firm.

The event was co-hosted by the Center for Information Technology Research in the Interest of Society, a research institute at several UC campuses — Berkeley, Davis, Santa Cruz and Merced — that provided mentors and about half of the hackathon’s hardware, including 3-D printers, laser cutters and power tools.

For Kathleen Gomez, a UC Berkeley sophomore and computer sciences major, Cal Hacks was her first hackathon and her “practice run” for YHacks at Yale University later this month.

“I just love the idea that people can come from all parts of the world just to make things,” Gomez said. “You put people together, and their ideas come to life.”