WEBVTT 00:00.460 --> 00:08.010 Are at the end of the section now so you should be doing some practice problems and start with the problem 00:08.010 --> 00:08.550 one. 00:09.980 --> 00:15.550 Write a program that will take you a number from the user and print the reverse of that number. 00:15.720 --> 00:24.420 So gives an example of the input and input is 1 2 3 4 and the output should be 4 3 2 1. 00:24.440 --> 00:27.940 So how would we approach this problem. 00:28.400 --> 00:40.580 Well you see here that if we could just get the last digit of the of the number each time. 00:40.580 --> 00:50.940 So if it could sort of break away this 4 and then sort of shift it to the last in a different number. 00:51.990 --> 00:59.160 And then again break away this three and then break this to and then break this one in sort of string 00:59.160 --> 01:02.020 it together by addition. 01:02.120 --> 01:06.320 So let's let me show you what I mean here. 01:06.320 --> 01:10.680 So let's say we had the number input number. 01:10.700 --> 01:19.230 So call it number and error and and have the reverse of the number we're incident to zero. 01:19.640 --> 01:22.490 So we do get it. 01:22.520 --> 01:25.680 This is from the user. 01:25.890 --> 01:31.460 These are number 01:38.100 --> 01:38.910 number 01:41.630 --> 01:45.180 in to do a loop. 01:45.280 --> 01:53.380 While we don't know really what the conditions should be at so let's just skip the condition for now 01:54.400 --> 01:59.470 and say reverse is 02:02.080 --> 02:07.790 what how would we break off this for. 02:08.230 --> 02:21.200 Well since these were all based 10 numbers if you if you actually get the remainder divided by 10. 02:21.260 --> 02:28.380 So if you divide this number by 10 and get the remainder you should get four. 02:28.400 --> 02:39.430 So you know how to do that and it's through the modulus operator number modulus 10 and so that will 02:39.430 --> 02:48.440 actually give you the last digit of the number so that we're not done. 02:48.590 --> 02:57.350 So we need to then take what we have previously and multiply it by 10. 02:57.350 --> 03:02.590 So this shifts it to the left by one place right. 03:02.600 --> 03:10.280 So this is the ones tens hundreds thousands right. 03:10.500 --> 03:21.360 And then we just add that and then in order to make it so that the number is less it will be one to 03:21.360 --> 03:26.350 three feet at the next iteration we'll divide that number by 10 03:31.420 --> 03:33.620 and you want to just print out the number 03:49.010 --> 03:54.220 urs Endal and let's run this. 03:54.230 --> 03:55.740 It's even. 03:55.880 --> 04:00.650 It's. 04:01.380 --> 04:06.800 So we still don't know what the condition is right for that. 04:06.810 --> 04:17.990 So really we're done when this number that we keep sort of breaking off pieces of is zero. 04:18.150 --> 04:29.990 So while number is greater than zero then we'll do this. 04:30.460 --> 04:31.230 Now it's Rinat 04:38.750 --> 04:43.970 in center 1 2 4 and there are Erse is 4 3 2 1. 04:43.970 --> 04:53.720 So again if you're not quite understanding how this works we're essentially taking the last digit of 04:53.720 --> 05:04.170 the number right here and we're adding it to what we had previously of the reverse. 05:04.170 --> 05:07.340 We start at zero of course because we don't have anything yet. 05:08.270 --> 05:11.320 So averse would be zero. 05:12.210 --> 05:16.100 Plus the last digit before. 05:16.400 --> 05:22.730 And then we multiply and then we then of course divide it by 10. 05:22.760 --> 05:27.670 So the next time would be 1 2 3 4 1 2 3. 05:28.430 --> 05:39.700 And then we take what we had before which is four times 10 to be 40 plus or 8 2 or 3 sorry. 05:40.560 --> 06:01.100 And then for the 0 2 and then 4 3 2 0 plus 1 and 3 2 1 K so that's sort of how it's working here. 06:04.500 --> 06:07.030 Hopefully that sort of makes sense. 06:11.560 --> 06:14.250 So let's go to the next problem. 06:16.210 --> 06:23.340 So says rent per game that takes into numbers from the user and Princess star pattern in a rectangular 06:23.340 --> 06:24.010 form. 06:24.030 --> 06:29.270 The first number will be the number of rows and the second number will be the number of columns. 06:29.460 --> 06:37.980 So an example here if rows was 5 in columns 6 then it would give out this star pattern. 06:37.980 --> 06:52.590 So there's six columns one two three four five six and five rows one two three four five or eight. 06:52.850 --> 06:54.940 So how would we do this. 06:54.980 --> 07:01.090 Let's just start with getting the rows and columns from the user rows. 07:02.440 --> 07:14.640 Zero were Cowen's so calls 0. 07:19.960 --> 07:23.520 Your number rose 07:26.970 --> 07:30.510 in rows right. 07:30.520 --> 07:33.100 And do any error checking for now. 07:37.260 --> 07:38.000 Enter 07:40.480 --> 07:42.500 number of columns. 07:48.350 --> 07:53.930 Number rows or columns. 07:54.580 --> 08:05.310 OK so now we have the rows and columns but how do we make it so that this pattern is outputted 08:12.080 --> 08:21.550 since we don't know how many columns and rows we have to output since it's given to us by the user. 08:21.710 --> 08:25.760 We're going to need more than one loop I think. 08:25.760 --> 08:32.520 So we're say into our four row. 08:32.690 --> 08:41.220 Or it's less than the number of rows is we're not using. 08:41.340 --> 08:50.240 We're not starting our loop at 1 using zero instead rope plus plus. 08:50.340 --> 08:55.660 So that's why we're not saying greater than or equal to you is saying we're less than or equal to or 08:55.680 --> 08:56.910 missing less than 09:01.100 --> 09:02.030 we're going to need. 09:02.030 --> 09:07.070 So we saw in the nested loop lecture that for every 09:09.690 --> 09:15.760 for every one iteration of the outer loop we can do many iterations of the. 09:15.840 --> 09:17.400 And that's exactly what we need to do. 09:17.400 --> 09:25.440 So we're actually going to loop through all the rows of each row and then we're going to do this many 09:25.770 --> 09:30.160 iterations of the inner k. 09:30.290 --> 09:33.710 So that will give us our star pattern. 09:33.920 --> 09:52.410 So we're going to save for C for Column C is less than number of columns plus in or CC out a star and 09:54.020 --> 10:00.450 in that after each row is finished then we do. 10:00.470 --> 10:03.290 And all 10:06.720 --> 10:07.560 just 10:11.540 --> 10:28.040 so you know this that's for example find 18:6 and there we go. 10:28.060 --> 10:35.610 So as one two three four five six and there's five ropes. 10:37.040 --> 10:44.730 We can do this any number really say seven in 10. 10:44.810 --> 10:53.490 1 2 three four five six 10 7 call ropes here. 10:53.580 --> 10:54.890 So I think this is working. 11:00.100 --> 11:07.830 So now on to the next one which is kind of similar is 11:12.790 --> 11:13.370 so. 11:13.390 --> 11:19.020 Write a program that takes in a number and Prince pyramid's star pattern. 11:20.840 --> 11:25.640 The pattern for five would look like this. 11:26.860 --> 11:32.400 So there would be one two three four five. 11:32.460 --> 11:43.910 And there's kind of it's like symmetric so you have the one for the top and then you have three five 11:43.910 --> 11:54.080 and seven eight nine. 11:54.210 --> 12:01.980 So it's sort of similar to how we did the star pattern above. 12:01.990 --> 12:05.770 So the first thing we should do is just get the number for easier 12:08.610 --> 12:12.560 see each means. 12:14.230 --> 12:15.050 Sure. 12:15.220 --> 12:15.970 Number 12:23.150 --> 12:31.680 get the number so we'll have to do some nested loops again. 12:32.650 --> 12:39.520 So how this is going to work is just like the above. 12:39.700 --> 12:53.330 We need to go through all the spaces first and the spaces sort of Windell as you get lower and lower. 12:53.380 --> 13:01.720 So there's one space here but there's no space at the bottom K so the spaces are actually kind of inverted 13:01.720 --> 13:06.660 to the pier made itself the kind. 13:06.720 --> 13:15.740 Think of it that way so let's go for Cincy. 13:15.780 --> 13:19.020 I whose T. 13:19.030 --> 13:26.460 0 is less than number. 13:26.580 --> 13:35.590 Plus plus again I'm starting at zero because typically we usually don't start at 1. 13:35.630 --> 13:36.830 We actually start at zero. 13:36.840 --> 13:41.280 Every every programmer kind of starts in zero thinking 13:44.410 --> 13:50.480 so first we're do we're actually going to print all the trailing spaces. 13:50.510 --> 13:54.820 How many spaces are there. 13:55.060 --> 14:09.650 So Jay and Jay is going to be less than something G plus plus And we're going to print out the space 14:09.650 --> 14:17.240 first and then we're going to loop through and print out all the stars. 14:17.280 --> 14:24.940 So are the stars here in print spaces here. 14:29.010 --> 14:29.580 It's 14:33.630 --> 14:35.950 so rescript to you. 14:37.130 --> 14:39.420 Ch g zero. 14:40.780 --> 14:47.080 J is less than something and A-plus plus 14:51.750 --> 14:57.490 out star. 14:58.010 --> 14:59.970 And here he said 15:03.130 --> 15:05.200 so we don't know that the conditions should be. 15:05.260 --> 15:08.220 So what should the condition be. 15:09.070 --> 15:15.860 So how many spaces exists in this case. 15:17.610 --> 15:29.150 So there's one two three four and then the fifth one is the star and then one two three and then one 15:29.150 --> 15:45.700 two and then one so really it's the number minus the current row minus one right. 15:46.200 --> 15:55.850 So if the number was five current row is zero let's say this is 0 0 with row the first row. 15:56.270 --> 16:00.710 Second third fourth OK 16:04.390 --> 16:11.210 in and so the number would be five. 16:11.210 --> 16:27.980 In this case 5 minus zero is five minus 1 which is 4 and 5 minus 1 minus 1 is 3 5 minus 2 minus 1 is 16:27.980 --> 16:29.230 2. 16:30.780 --> 16:37.520 So that's kind of one way we can think about figure out all the space is. 16:37.530 --> 16:46.620 And for this one it's actually pretty simple it's always just two times the row last one 16:51.200 --> 16:57.070 K so the row here would be zero. 16:57.380 --> 17:01.470 So two times that is zero. 17:01.720 --> 17:04.390 And then plus 1 is 1. 17:04.390 --> 17:06.190 So two times the row here. 17:06.230 --> 17:23.290 So the row is 1 and 2 times one 2 plus 1 is 3 and 2 times the row here is four plus one is 5 Cancion. 17:23.360 --> 17:30.570 So let's run this and see fun. 17:31.030 --> 17:31.820 And there you go 17:34.860 --> 17:39.790 of more 7 or something. 17:40.870 --> 17:43.660 Is k. 17:43.690 --> 17:48.160 So in the next section we're going to start talking about functions.