1 00:00:00,510 --> 00:00:03,030 OK, so how do we do this searching problem? 2 00:00:03,060 --> 00:00:09,990 Well, we're going to go over the most basic, rudimentary style of search, which is called linear 3 00:00:10,050 --> 00:00:12,990 search or sequential search and all. 4 00:00:12,990 --> 00:00:19,050 It is literally just moving one by one from left to right through an array of vector and looking for 5 00:00:19,050 --> 00:00:20,900 the thing that we're interested in. 6 00:00:20,910 --> 00:00:22,040 So this is pretty straightforward. 7 00:00:22,050 --> 00:00:24,820 You probably were able to figure this out. 8 00:00:24,840 --> 00:00:26,910 This one was quite a bit easier than the other ones. 9 00:00:28,140 --> 00:00:32,460 And you know, that's the most straightforward way to find something is just linear search. 10 00:00:32,700 --> 00:00:34,950 So let's go ahead and go in here. 11 00:00:34,950 --> 00:00:39,690 I've already written most of a program because this is stuff we've already done. 12 00:00:39,700 --> 00:00:42,330 So what I do is I just make a vector here. 13 00:00:42,900 --> 00:00:48,150 I have an integer that I read into for those five numbers that go into the vector. 14 00:00:49,470 --> 00:00:53,160 Then I have number one and number two, which is the two numbers that get taken from the user to make 15 00:00:53,160 --> 00:00:53,730 the sum. 16 00:00:54,770 --> 00:01:01,460 So in this loop right here, it's just what we've been doing over and over so far, which is getting 17 00:01:01,460 --> 00:01:04,050 five numbers and reading them into the vector here. 18 00:01:05,060 --> 00:01:09,430 Then we say into two integers to be summed and we read in two more integers. 19 00:01:09,440 --> 00:01:12,290 And then what I check here is, I say if. 20 00:01:13,290 --> 00:01:22,050 Linear search and I send this vector and the sum of number one, plus them to both as arguments to this 21 00:01:22,050 --> 00:01:27,510 and linear search function, and that function is up here, which I have not written yet, but you notice 22 00:01:27,510 --> 00:01:35,490 that it takes a vector of integers by reference here, passing it by reference and then we have an integer 23 00:01:35,490 --> 00:01:36,690 in this pass by value. 24 00:01:38,460 --> 00:01:46,500 So it says if this function returns true, then this whole statement here will be replaced by true and 25 00:01:46,500 --> 00:01:52,500 it will evaluate to true, and it will run the code inside here, which says that no one less known 26 00:01:52,500 --> 00:01:55,830 to equals the sum is in the list. 27 00:01:56,010 --> 00:02:00,120 Else we're going to say the same thing to say is not in the list. 28 00:02:01,200 --> 00:02:01,610 All right. 29 00:02:01,650 --> 00:02:07,650 So pretty straightforward, I'm just going to go ahead and implement this function is a very straightforward 30 00:02:07,650 --> 00:02:08,140 function. 31 00:02:08,160 --> 00:02:09,280 It's just going to be simple. 32 00:02:09,280 --> 00:02:12,270 I live where I do the same style. 33 00:02:12,300 --> 00:02:17,730 Live or die with zero is less than the. 34 00:02:17,970 --> 00:02:22,140 I'm going to say V because we're passing the vector as the variable V. 35 00:02:22,500 --> 00:02:29,910 Some say we that size I + + and then I'm just going to have some f check in here. 36 00:02:29,910 --> 00:02:32,490 And I'm just going to say if v ie 37 00:02:35,020 --> 00:02:39,810 is equal to N, then I'm just going to return true. 38 00:02:43,590 --> 00:02:47,730 And I'm going to live through this whole vector, and so if I ever see. 39 00:02:49,690 --> 00:02:56,020 That the current position in the vector is equal to the number that was passed to this function. 40 00:02:56,320 --> 00:03:00,100 Then I'm going to immediately return from the function and I'm going to return truth to notice that 41 00:03:00,100 --> 00:03:02,110 this is a Boolean type function. 42 00:03:02,140 --> 00:03:03,700 This is the return type it's bore. 43 00:03:04,960 --> 00:03:08,440 So I'm going immediately, just break out of the whole function and return true. 44 00:03:09,690 --> 00:03:19,080 If I'm able to successfully make it through the whole loop, so up to, you know, we got size minus 45 00:03:19,080 --> 00:03:20,970 one basically and I stopped the loop. 46 00:03:21,300 --> 00:03:27,000 That means that I never found an inside of the vector. 47 00:03:27,510 --> 00:03:34,110 And so in that case, I'm going to basically be down here after this last bracket for the loop. 48 00:03:34,110 --> 00:03:39,990 And so I can just return false at this point because that means that I did not find the item I was looking 49 00:03:39,990 --> 00:03:40,380 for. 50 00:03:41,400 --> 00:03:44,250 And so this will return either true or false. 51 00:03:45,000 --> 00:03:51,360 And that will set us up nicely right here to check to see whether the number was in the list or not. 52 00:03:51,390 --> 00:03:52,950 So let's go ahead and run this. 53 00:03:52,950 --> 00:03:56,400 So I'm just going to for a plus linear search. 54 00:03:57,210 --> 00:04:03,540 So I'll say, let's start out and I'll run this and let's just 55 00:04:06,660 --> 00:04:07,890 put some numbers in here. 56 00:04:07,890 --> 00:04:15,930 So we have four seven eight one three, and I'm just going to say, how about we do five and three? 57 00:04:16,740 --> 00:04:18,890 So five plus three is eight is in the list, right? 58 00:04:18,900 --> 00:04:19,740 Because eight is here. 59 00:04:19,740 --> 00:04:28,110 So let's go ahead and try this again, and I'll put the same one I to save for seven eight one three. 60 00:04:28,710 --> 00:04:32,310 And let's put something like, you know. 61 00:04:33,470 --> 00:04:36,710 Nine and three. 62 00:04:37,550 --> 00:04:39,950 So, Nancy is one that is not in the list. 63 00:04:40,870 --> 00:04:48,060 All right, so just have those two examples there, it's often best to do a lot more input and testing 64 00:04:48,060 --> 00:04:53,340 with your programs just to be sure that everything is working correctly, but I'm just going to leave 65 00:04:53,340 --> 00:04:54,150 it at this. 66 00:04:54,150 --> 00:04:56,820 So if you are able to figure that out, great. 67 00:04:56,850 --> 00:05:04,860 If not, you know, it's you're probably just overthinking it because really, you can just use that 68 00:05:04,860 --> 00:05:10,410 linear surge to loop through with just a basic foil loop and you don't have to do anything else besides 69 00:05:10,410 --> 00:05:19,110 that, although there is a more efficient way to search for items in a list, and that's what we're 70 00:05:19,110 --> 00:05:27,240 going to be going over in the next lecture, and it actually requires us to first sort list. 71 00:05:27,270 --> 00:05:30,750 So with that, I will see you in the next lecture.