A group of Silicon Valley high school students captured medals at the ninth annual China Girls Mathematical Olympiad, earning top prizes for the United States in the competition involving 190 representatives from 48 teams.

Four California high school students, along with three other Americans, won medals at the international competition, which took place in Shijiazhuang, the capital of China's Hebei province.

The competition was completed Thursday.

Shiyu "Jing-Jing" Li of Sunnyvale and Lynnelle Ye of Palo Alto earned gold medals, and Cynthia Day of San Jose earned a silver.

Ye was a member of the U.S. team that scored second overall in the tournament, behind a team from the host country.

Rankings for the teams beyond the first two have not yet been released.

The two gold medal winners will be keeping their talents in the Bay Area: Li, who graduated from Cupertino High School, will be heading to UC Berkeley, and Ye, who graduated from Palo Alto High School, will attend Stanford University.

Day is currently a junior at Lynbrook High School.

Four other girls on U.S. teams earned honors, including bronze medalist and senior Adisa Kruayatidee of Stevenson Ranch, a community in Los Angeles County.

Rather than testing students on rapidly completing many problems or on their mastery of advanced mathematics, the contest emphasized creative thinking.

Only eight problems were administered over a two-day exam, with an hour for each mind-bender.

"The most important thing it requires is imagination -- it's not the kind of problems you see in a high school book," said Robert Bryant, director of Berkeley's Mathematical Sciences Research Institute, which organized the trip.

The year may have been the best yet for the Americans, who have been led by coach Zuming Feng since the country's debut at the competition in 2007.

The seven medalists in gold and silver, including five golds, outdid American teams from any prior year; the team had eight total medalists in 2008, but five were bronze.

This year's team members were among the top female finalists in the 2010 USA Mathematical Olympiad.

Feng noted the ingenuity of this year's group. He described Ye's solution to one problem as "better than the original solutions provided by the problem committee, for problem 4, the hardest problem on the exam."

Before her work on the exam, Ye wrote on a blog kept by the team that she deeply appreciated the opportunities provided by the group's travel.

She said she was pleased to participate in an educational science workshop in her downtime, teaching math to other high school students.

"I feel extremely lucky to have gotten the chance to meet these kids," Ye wrote on the team blog. "If we do nothing else the entire trip, this opportunity has already made the whole thing worthwhile."