1 00:00:00,467 --> 00:00:01,050 PROFESSOR: Hi. 2 00:00:01,050 --> 00:00:02,950 Have you found it particularly difficult 3 00:00:02,950 --> 00:00:05,630 to find a specific item in your house? 4 00:00:05,630 --> 00:00:07,830 Let's say you're looking for a pair of gloves, 5 00:00:07,830 --> 00:00:11,140 but you just can't find it, and you spend the entire afternoon 6 00:00:11,140 --> 00:00:12,660 looking for it. 7 00:00:12,660 --> 00:00:15,060 Well, you've just encountered the same problem 8 00:00:15,060 --> 00:00:17,850 that companies like Google or Microsoft 9 00:00:17,850 --> 00:00:20,560 encounter every single day. 10 00:00:20,560 --> 00:00:22,717 And that's the problem of search. 11 00:00:22,717 --> 00:00:24,550 Just like a house, where you store thousands 12 00:00:24,550 --> 00:00:28,760 of different items, Google stores 45 billion index pages 13 00:00:28,760 --> 00:00:30,130 of information. 14 00:00:30,130 --> 00:00:32,659 And if every page was a sheet of paper 15 00:00:32,659 --> 00:00:34,630 and we stacked them up real high, 16 00:00:34,630 --> 00:00:40,322 we'd create a tower 600 times taller than Mount Everest. 17 00:00:40,322 --> 00:00:42,510 Well, how can Google find my results 18 00:00:42,510 --> 00:00:44,950 so quickly when I find it so difficult 19 00:00:44,950 --> 00:00:47,490 to find a pair of gloves? 20 00:00:47,490 --> 00:00:49,060 Well, searching on Google is kind 21 00:00:49,060 --> 00:00:53,480 of like looking for a person in a big school. 22 00:00:53,480 --> 00:00:56,390 Let's say you're looking for James in a row of classrooms. 23 00:00:56,390 --> 00:00:58,100 Well, the easiest method would be 24 00:00:58,100 --> 00:01:03,440 to go to every classroom nearest to you until you find James. 25 00:01:03,440 --> 00:01:06,570 There's a better method when it's binary search. 26 00:01:06,570 --> 00:01:08,430 Let's say the students were arranged 27 00:01:08,430 --> 00:01:13,540 from A to Z in the increasing number of the classrooms. 28 00:01:13,540 --> 00:01:16,300 And let's say we head to the middle room first. 29 00:01:16,300 --> 00:01:19,140 And if the person in the middle room isn't James, 30 00:01:19,140 --> 00:01:21,870 but his name starts with the letter before J, 31 00:01:21,870 --> 00:01:23,140 we head to the right. 32 00:01:23,140 --> 00:01:25,290 If not, we head to the left. 33 00:01:25,290 --> 00:01:29,700 We then approach the middle room in the newly sectioned area. 34 00:01:29,700 --> 00:01:31,580 We rinse and repeat. 35 00:01:31,580 --> 00:01:35,080 Eventually, we will find James, just like the first method. 36 00:01:35,080 --> 00:01:40,610 But we find him in a much faster way with the second method. 37 00:01:40,610 --> 00:01:42,720 How much faster would that be? 38 00:01:42,720 --> 00:01:45,810 Well, that depends on the number of students in the school. 39 00:01:45,810 --> 00:01:47,430 Let's say there are 500 students, 40 00:01:47,430 --> 00:01:48,950 and we're looking for one. 41 00:01:48,950 --> 00:01:51,600 It will take about 80 minutes in the first method, 42 00:01:51,600 --> 00:01:55,030 but 1 and 1/2 minutes with binary search. 43 00:01:55,030 --> 00:01:58,150 Let's say there are 1,000 students in the school. 44 00:01:58,150 --> 00:02:01,510 It would take 160 minutes with the first method, 45 00:02:01,510 --> 00:02:05,175 but 1.6 minutes with the second method. 46 00:02:05,175 --> 00:02:08,550 Now, that's a whole lot of difference. 47 00:02:08,550 --> 00:02:10,304 So a name is just a word. 48 00:02:10,304 --> 00:02:13,870 But Google searches a combination of words, 49 00:02:13,870 --> 00:02:16,920 making it a little bit more complicated. 50 00:02:16,920 --> 00:02:19,550 So just like how we identified the first letter 51 00:02:19,550 --> 00:02:22,000 of each alphabet of the name, Google 52 00:02:22,000 --> 00:02:26,400 identifies 200 unique factors, making your search terms 53 00:02:26,400 --> 00:02:28,090 faster. 54 00:02:28,090 --> 00:02:30,730 If you recall, the effectiveness of binary search 55 00:02:30,730 --> 00:02:34,150 depends on the prearrangement of data. 56 00:02:34,150 --> 00:02:36,440 And that's why computer scientists are actively 57 00:02:36,440 --> 00:02:40,540 looking for ways to sort, manage, and eventually retrieve 58 00:02:40,540 --> 00:02:43,560 data faster and better. 59 00:02:43,560 --> 00:02:47,340 In the same way, the TV remote goes near the TV, 60 00:02:47,340 --> 00:02:51,530 the shoes go to the shoe rack, the coats go into the cupboard, 61 00:02:51,530 --> 00:02:54,560 and the winter gloves go into the winter jacket. 62 00:02:54,560 --> 00:02:55,550 Aha. 63 00:02:55,550 --> 00:02:58,340 So that's where my gloves are.