PROFESSOR: Hi, have you found it particularly difficult to find
a specific item in your house?
Let's say you're looking for a pair of gloves,
but you just can't find it, and you spend your entire afternoon
looking for it.
Well, you've just encountered the same problem
that companies like Google or Microsoft
encounter every single day.
And that's the problem of search.
Just like a house which stores thousands of different items,
Google stores 45 billion index pages of information.
If every page was a sheet of paper
and we stack them up real high, we'll create a tower 600 times
taller than Mount Everest.
Well, how can Google find my results
so quickly when I find it so difficult
to find a pair of gloves?
Well, searching on Google is kind
of like looking for person in a big school.
Let's say you're looking for James in a row of classrooms.
One of the easiest method would be
to go to every classroom nearest to you until you find James.
There's a better method called binary search.
Now, let's say the students were arranged from a to z,
one in each classroom.
We would then go to the middle room
first and see if James is there.
And if James isn't there we will look
at the first letter in the name, and if the letter is
before j, we head to the right, if not, we head to the left.
We would then approach the middle room
in the newly sectioned area.
Eventually we will repeat the process over and over again
until we find James.
Now, this is just like the first method, but it's at a much,
much faster rate.
How much faster would that be?
Well, that depends on the number of students in the school.
Let's say there are 500 students and we're looking for one.
It will take about 80 minutes in the first method,
But one and a half minutes with binary search.
But let's say there are 1,000 students in the school.
It would take 160 minutes with the first method,
but 1.6 minutes with the second method.
Now that's a whole lot of difference.
So a name is just a word.
But Google searches a combination of words,
making it a little bit more complicated.
So just like how we identified the first letter
of each alphabet of the name, Google
identifies 200 unique factors making your search terms
faster.
Well, if you recall, the effectiveness of binary search
depends on the prearrangement of data.
And that's why computer scientists are actively
looking for ways to sort, manage, and eventually retrieve
data faster and better.
In the same way, the TV remote goes near the TV,
the shoes go to the shoe rack, the coats go into the cupboard,
and the winter gloves go into the winter jacket.
Aha, so that's where my gloves are.