1 00:00:00,790 --> 00:00:03,190 The following content is provided under a Creative 2 00:00:03,190 --> 00:00:04,730 Commons license. 3 00:00:04,730 --> 00:00:07,030 Your support will help MIT OpenCourseWare 4 00:00:07,030 --> 00:00:11,390 continue to offer high quality educational resources for free. 5 00:00:11,390 --> 00:00:13,990 To make a donation or view additional materials 6 00:00:13,990 --> 00:00:17,860 from hundreds of MIT courses, visit MIT OpenCourseWare 7 00:00:17,860 --> 00:00:18,820 at ocw.mit.edu. 8 00:00:22,589 --> 00:00:24,130 ANA BELL: So the question is, we have 9 00:00:24,130 --> 00:00:30,460 the string s is the string 600 is 6 triple 1 and 6 triple 2. 10 00:00:30,460 --> 00:00:33,204 So we're going to create the string here. 11 00:00:33,204 --> 00:00:34,495 It's initially an empty string. 12 00:00:40,040 --> 00:00:46,530 I want to mention that the plus equals-- for example, 13 00:00:46,530 --> 00:00:49,640 if I say a plus equals 1. 14 00:00:49,640 --> 00:00:54,149 This is equivalent to a is equal to a plus 1. 15 00:00:54,149 --> 00:00:56,440 We've seen this a couple of times before-- last lecture 16 00:00:56,440 --> 00:00:58,710 and the last lecture before that. 17 00:00:58,710 --> 00:01:04,849 So all this means here, this line here, 18 00:01:04,849 --> 00:01:07,280 is we're going to take the previous string that we have, 19 00:01:07,280 --> 00:01:09,680 and we're just going to add it to itself, 20 00:01:09,680 --> 00:01:11,460 plus the last letter. 21 00:01:11,460 --> 00:01:17,900 So the first thing we're going to have is going to be new_str 22 00:01:17,900 --> 00:01:19,310 is equal to 2. 23 00:01:22,080 --> 00:01:24,180 Then this line here is going to say now I'm 24 00:01:24,180 --> 00:01:28,650 going to add to the two that I already have, 25 00:01:28,650 --> 00:01:31,380 the element at position 0, which is a 6. 26 00:01:31,380 --> 00:01:34,740 So I'm going to have 6. 27 00:01:34,740 --> 00:01:40,890 Then I'm going to add to that, the element at index 4. 28 00:01:40,890 --> 00:01:42,390 So I'm starting count from 0. 29 00:01:42,390 --> 00:01:47,730 So this is 0, 1, 2, 3, 4. 30 00:01:47,730 --> 00:01:48,480 So that's a space. 31 00:01:51,240 --> 00:01:54,760 And I'm going to go-- notice I have 4, and then 32 00:01:54,760 --> 00:01:55,790 nothing in the middle. 33 00:01:55,790 --> 00:02:00,130 So my stop is going to be length s by default. 34 00:02:00,130 --> 00:02:02,270 And I'm going to take every 30 characters. 35 00:02:02,270 --> 00:02:06,460 Now every 30 is longer than the actual string I have. 36 00:02:06,460 --> 00:02:12,307 So we're just going to end at the end of the string. 37 00:02:12,307 --> 00:02:14,515 So the next thing that we're going to add is a space. 38 00:02:17,784 --> 00:02:19,450 And then the last thing we're doing here 39 00:02:19,450 --> 00:02:21,440 is we're starting at 13. 40 00:02:21,440 --> 00:02:25,360 So now I'm going to have to count 13-- 0, 1, 2, 3, 4, 5, 6, 41 00:02:25,360 --> 00:02:29,130 8, 9, 10, 11, 12, 13. 42 00:02:29,130 --> 00:02:30,850 That's the 1. 43 00:02:30,850 --> 00:02:34,990 I'm going to go backward, because of this minus 1. 44 00:02:34,990 --> 00:02:38,340 And I'm going to go backward until 10, but right 45 00:02:38,340 --> 00:02:41,196 before 10-- so 1 less than 10. 46 00:02:41,196 --> 00:02:44,660 So I'm going to do 100. 47 00:02:44,660 --> 00:02:47,654 So this one, this 0, and then this 0. 48 00:02:47,654 --> 00:02:49,320 Then I'm going to print this new string. 49 00:02:52,794 --> 00:02:53,710 I think this is right. 50 00:02:53,710 --> 00:02:57,760 If you paste it into Spider, it should give you 26 space 100. 51 00:02:57,760 --> 00:03:01,550 So I think most of the class got it right. 52 00:03:01,550 --> 00:03:03,020 I think, yes. 53 00:03:03,020 --> 00:03:04,570 Perfect.