WEBVTT 00:01.050 --> 00:02.790 So let's solve the next question. 00:03.420 --> 00:11.370 It is regarding a Caesar cipher is a simple substitution cipher in which each letter of the plaintext 00:11.670 --> 00:16.290 is substituted with a letter found by moving in places down the alphabet. 00:16.830 --> 00:22.320 So, for example, let's assume the input plain text as B, C, D, X, Y or Z. 00:22.650 --> 00:25.740 So we've shifted by invisible to food. 00:26.100 --> 00:32.490 Let's see what you find is equal before then will be changed to e b will be changed to f, c will be 00:32.490 --> 00:33.360 changed to G. 00:33.630 --> 00:35.040 They will be changed to H. 00:35.160 --> 00:35.790 I'm sure. 00:36.660 --> 00:40.260 And you'll excuse me change to be y to see that 2D. 00:41.100 --> 00:45.780 So here and will be the value which will be provided separately. 00:46.600 --> 00:47.970 I think so. 00:47.970 --> 00:52.230 I guess here is to write a function that accepts the argument. 00:52.260 --> 00:59.340 One is the text, which is something like this, and another value, a number by which the letters need 00:59.340 --> 01:00.110 to be shifted. 01:00.150 --> 01:01.350 That is in here. 01:02.340 --> 01:05.610 Now, this function will return an encrypted string. 01:05.850 --> 01:12.450 Will all the letters transform from this form to this function, while all the punctuations and white 01:12.450 --> 01:14.340 spaces will remain unchanged? 01:15.270 --> 01:16.680 So try this out. 01:17.190 --> 01:22.920 And you can pause the video now and unpause in case you want to see the solution for them. 01:33.720 --> 01:36.030 Now, let's go ahead and that's why I've been in problem. 01:37.170 --> 01:39.580 So this is a string related problems. 01:39.580 --> 01:43.320 So for this, we will need to import those drinks library. 01:43.650 --> 01:51.000 So let's say import strength as s d. 01:52.650 --> 02:07.410 I am strength or let me make this next in String's Library, we already have letters which are already 02:07.410 --> 02:13.800 present in lowercase and a book bookcase fought so we can download the ones, so we can simply say letters 02:14.910 --> 02:15.540 is equal. 02:15.550 --> 02:23.880 Those green dot sky underscored lowercase. 02:25.980 --> 02:27.810 Let's see, what do we have in letters? 02:28.980 --> 02:32.370 So here we have all the letters in lowercase. 02:33.510 --> 02:37.060 Now let's get the number in. 02:37.080 --> 02:40.960 So let's get the number in as an input now. 02:40.980 --> 02:42.470 And we're getting it as an input. 02:42.480 --> 02:44.460 We need to convert it into integer also. 02:44.460 --> 02:45.360 So we say in 02:48.660 --> 02:57.150 input and insight input, we say how many shifts? 03:01.690 --> 03:04.150 And the person can enter the number of ships they want. 03:06.170 --> 03:08.590 Now we need to shift. 03:08.620 --> 03:09.880 Each and every year. 03:10.150 --> 03:15.160 So let's try to create something as shifted here. 03:15.160 --> 03:18.190 So we create another list with shifting regulators. 03:18.550 --> 03:19.450 So let's see. 03:19.460 --> 03:25.840 Shifted and shifted will be equal to now. 03:25.840 --> 03:27.480 What will we have in shifted? 03:27.490 --> 03:31.150 So inch of third, we will have a BKD. 03:31.240 --> 03:36.010 So let's say there are a number of the number of letters which we have shifted by four. 03:36.580 --> 03:38.410 So when we shift by four. 03:42.990 --> 03:51.300 Then we show these by fall, we will have these letters, as it does, but they will be shifted in the 03:51.300 --> 03:51.630 list. 03:51.900 --> 03:54.450 So the index will be a little different. 03:54.990 --> 04:00.750 So what can we do is we can create the list by letters and in letters. 04:00.750 --> 04:06.770 We will get only the values which will be having, let's say, shifted by. 04:06.780 --> 04:12.810 And so we can simply say we want the letters to start from in and hope delivery. 04:14.310 --> 04:15.390 What do we get here? 04:15.540 --> 04:18.540 Let's shift it and let's practice. 04:19.230 --> 04:20.340 So let's step four. 04:21.310 --> 04:25.020 So it gives me these shuffled ones. 04:25.410 --> 04:28.200 Now then we try to map these. 04:28.470 --> 04:33.150 So Z will be mapping of some other character. 04:33.390 --> 04:36.810 But the last few characters are still missing their mappings. 04:38.070 --> 04:40.770 So for that or let me print it for you. 04:41.250 --> 04:50.330 Let's print that for, you know, let's say four. 04:51.600 --> 04:55.560 So you can see this one is shorter than this one. 04:57.660 --> 05:00.510 So what if we have F E for B? 05:00.510 --> 05:02.700 We have F for C, we have T. 05:03.060 --> 05:06.990 But we do not have anything for WXYZ. 05:07.110 --> 05:16.980 So for that, we need to add these characters in the at the end so we can do that by simply adding letters 05:17.910 --> 05:20.790 from the very beginning, still in in time. 05:21.870 --> 05:22.680 So let's see. 05:22.680 --> 05:23.370 What do we get? 05:24.360 --> 05:25.200 That's a fourth. 05:25.950 --> 05:29.140 So here you can see this is this mapping which we have got. 05:29.160 --> 05:31.110 This is the mapping which we have generated. 05:31.500 --> 05:35.970 So when we say for ship, it will replace this by this, this by this. 05:36.240 --> 05:41.490 Now, below, we have created what the sequence should be, but we have still not told that whenever 05:41.490 --> 05:44.790 you find a replaceability, that is still not been done. 05:45.270 --> 05:49.820 So for that, actually, we have to create a map function. 05:49.830 --> 05:54.320 So what the mapper does is it will basically map those values to each other. 05:54.330 --> 05:56.250 So let's create the map of function here. 05:57.780 --> 06:02.300 So we say map book equals. 06:02.940 --> 06:03.930 It's a dictionary. 06:04.410 --> 06:06.840 So we are creating a dictionary in the dictionary. 06:06.840 --> 06:07.440 What do we have? 06:07.440 --> 06:08.490 We have letters. 06:09.420 --> 06:11.610 And in the letters, we take index. 06:13.800 --> 06:19.320 And with it, we say shifted and index. 06:19.350 --> 06:31.600 I for I in range of all letters. 06:32.370 --> 06:35.250 What it simply does is its print map. 06:37.950 --> 06:42.420 So for each and every character, you have created a mapping. 06:44.130 --> 06:49.250 Right now, what we need to do further is let's say we have any text, OK? 06:49.260 --> 06:56.970 Let's say we have a text is going to do this. 06:57.660 --> 06:58.620 Before the 07:01.140 --> 07:04.890 door was saying, OK, 07:07.860 --> 07:09.700 this is a decent sentence. 07:09.720 --> 07:16.710 Now, if you want to transform it, we can simply say so here we get each and every alphabet. 07:17.220 --> 07:20.340 Now, I want to get alphabet from the map itself. 07:20.790 --> 07:25.500 So I will t or let's get the alphabet one by one. 07:25.800 --> 07:28.050 Now, if the map is present. 07:35.400 --> 07:39.300 In my book, Dark Keys. 07:41.500 --> 07:46.690 Then it should return my bush. 07:49.700 --> 08:00.980 It's like if it is not present, is it should simply read-only as hazardous. 08:03.420 --> 08:09.390 So this is what we have now, this still needs to be converted into a sentence full so we can simply 08:09.390 --> 08:09.720 say 08:13.200 --> 08:17.870 not join join me to break it. 08:19.560 --> 08:20.550 So let's run this. 08:21.270 --> 08:25.590 So what it simply did is it converted it and joined. 08:25.740 --> 08:26.610 What have we done? 08:26.910 --> 08:32.760 We have simply created a map, but then we have created a dictionary, kind of all of what needs to 08:32.820 --> 08:33.990 be converted to what. 08:34.440 --> 08:39.630 Then we check if the character which we are looking for is present in the map or the keys. 08:40.020 --> 08:41.910 Then we simply put the map. 08:41.910 --> 08:45.180 But here, if it is not there, then we put the alphabet. 08:45.600 --> 08:51.510 So wherever we have these exclamation marks or those pieces, they will be one thing as it is. 08:51.720 --> 08:57.960 Otherwise, it will try to insert the map or key that because it will try to insert the value of the 08:57.960 --> 08:58.170 map. 09:00.000 --> 09:00.510 That's it. 09:00.750 --> 09:03.120 So this is how we solve this particular problem. 09:04.200 --> 09:07.890 And then you can convert it into a function or anything you want. 09:08.430 --> 09:10.990 So that is something which you can do on top of this.