All language subtitles for 27. Extra Recursion 4 - Find if Digits are Ascending, Descending, or not - Question

All right.

What is going on, ladies and gentlemen, and welcome to this video where we are going to develop a

recursive function that receives an integer number.

OK, so we are going to do some recursion.

Another exercise and you are going to become even better and you will get more knowledge and more experience

working with recursion.

So what do you have to do is to develop a recursive function that receives an integer number and all

the functions you do is it should observe the digits from left to right.

And then based on the order of these digits, the function should return one.

If the digits from left to right are very ascending, the function should return minus one if the digits

from left to right are very descending.

And the function should return is zero.

Otherwise.

So simply saying we look at the digits from left right and we say if they are incrementing from left

to right, we will return one if they are a discriminating from left to right.

We will return minus one.

And if we have any other case, like if maybe two digits are the same or basically if two digits, we

have one digits smaller than the other and then we have another digit smaller than this one.

Then basically, we can say that it's definitely not very ascending, neither.

It's also not a very descending a sequence of digits.

OK.

So.

We know that this exercise can be easily solved just by using some loops, right, we can use some loop

iterating over each and every one of the digits.

Probably we will do also the same here, but for now, because we are requested to develop a function,

a recursive function.

We will say, at least at the beginning, we will say, OK, we have.

First, the idea of using loops, let's take loops, put them aside and try to solve it in another way,

in a recursive manner.

When we are going to take a bigger problem, splitting it up to smaller problems, some problems in

making conclusions based on this day vision.

OK, that's what we are requested to do to write the recursive function.

Also, a couple of assumptions that we need to take into account is, first of all, that we can take

some assumption that the initial noun verb to function is going to receive is basically has more than

two digits, two digits and beyond.

OK, it's not just one one digit number.

If it was like if we had to take into consideration all the possibilities.

So basically just there were a couple of few changes that we would need to add.

But for now, we will assume that our now is at least of two digit size and all digits in some are different.

OK.

That's very important to take into account because if not, we would need to add a few more lines of

code.

That's basically something that we can do, but for now, that will be sufficient for us to work and

to develop these recursive function with these pretty much nice assumptions.

OK, so we have initial number of two plus digits and all digits in some are different.

No pair of digits are the same, meaning all the digits are going to be different.

In this example, we will simply use it like this.

OK, so all the digits will be different.

So for example, if we have, this number now equals two one two four, then we can say that the function

should return one.

Because if we take a look at the digits from left to right, we will see that the digits are very ascending.

If we will take a look at this one, we will see that although the digits seem to be very ascending,

the last digit is descending.

And that means that the sequence of these digits from left to right is neither very ascending nor very

descending.

Final option is when, whenever we return, minus one is when we have from left to right.

If we take a look at the digits and we see that they are very descending, meaning for every pair of

digits that we take, the left digit will be greater than the right one.

OK, so that's the function that you have to develop.

Take some time to think about what should be the solution.

How to approach this exercise.

Write some code on your own.

Try to run it using some function, some main call for these function and make sure that your idea works

and then compare it with the results that we are going to do together.