The Anita Borg Institute

The Quicksort Algorithm

Quicksort is the fastest known comparison-based sorting algorithm (on average, and for a large number of elements), requiring O(n log(n)) steps. By convention, n is the number of elements to be compared and big O is a function of those elements. Quicksort is a recursive algorithm which first partitions an array according to several rules:

Pick an element, called a pivot, from the array.

Reorder the array so that all elements with values less than the pivot come before the pivot, while all elements with values greater than the pivot come after it (equal values can go either way). After this partitioning, the pivot is in its final position. This is called the partition operation.

Recursively apply the above steps to the sub-array of elements with smaller values and separately to the sub-array of elements with greater values.

Quicksort was invented by Tony Hoare and has undergone extensive analysis and scrutiny, and is known to be about twice as fast as the next fastest sorting algorithm. In the worst case, however, quicksort is a slow n² algorithm (and for quicksort, “worst case” corresponds to already sorted). (Click this link for an example of the Quicksort Algorithm written in C)

Protopiper

Fabrication prototyping tech from the HPI Human Computer Interaction Lab is a computerized tapegun that can produce 3D forms to help visualize objects in spaces:

Protopiper is a computer aided, hand-held fabrication device that allows users to sketch room-sized objects at actual scale. The key idea behind protopiper is that it forms adhesive tape into tubes as its main building material, rather than extruded plastic or photopolymer lines. Since the resulting tubes are hollow they offer excellent strength-to-weight ratio, thus scale well to large structures. 

In honor of the 2015 Day of the Girl Child, check out this new DipNote by Catherine Russell, the Ambassador-at-Large for Global Women’s Issues. 

Girls Don’t Run the World, Yet

by Catherine Russell

I meet with adolescent girls almost everywhere I travel, and I find that no matter what country I’m visiting, the optimism of girls is universal. Adolescent girls believe in themselves and in their own potential to make the world a better place to live.

As the international community works to empower adolescent girls by tackling the challenges they face – the gender-based violence, the cultural assumptions that girls are worth less than boys, the lack of access to quality education, and so on – we need to remember that girls themselves are important, powerful partners in our work.

Here are five inspiring girls who are proof that girls can and do lead the way for gender equality and girls’ empowerment.

Since she was eight years old, Jimena has taught other girls about human rights, girls’ health, and education in Guatemala. Today she is still a peer educator, but she’s also an educator of adults, who need to hear why girls are worth the investment.  

Tisungeni is 13 years old. She left her home in Malawi for the first time to travel to New York City for the UN General Assembly, where she shared her experiences of working to pay for her education and advocating for girls’ priorities. It was an honor to meet her.  

When I visited the Alliance Girls High School in Kenya this summer, I met with many girls who talked about how their education helped them overcome challenges. One of the themes I took away from that visit was how stereotypes hold back girls from attending school or doing their best in the classroom. 

Sangita attends one of the best universities in Mumbai. She’s in the top 5 percent of her class. But she’s had to overcome incredible challenges to get where she is, from poverty to perceptions that girls don’t belong in school. In addition to her studies, Sangita is also an advocate for Magic Bus, an NGO which uses sports as a catalyst for education.  

President Obama focused on women and girls during his trip to Kenya and Ethiopia this summer. This quote from Sandra, a 16-year-old student at a high school in Nairobi, summed up how powerful his remarks truly were.

For more information:

See how the international community is commemorating the 2015 International Day of the Girl Child.

Find out how the United States is empowering girls to reach their full potential through the Let Girls Learn Initiative.

Submit a photo and share what you learned in school, to support the 62 million girls around the world don’t have the opportunity to go to school.