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Let's now get into the code for solving the monotonic array question.

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Okay.

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So first over here we're going to check whether the input array which is given to us does not have any

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elements.

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And remember in the previous video we had asked the interviewer that whether we should consider an empty

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array to be monotonic.

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And the reply that we got was that yes, an empty array should be considered monotonic.

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So let's have a check for that over here.

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So I will say if array dot length is equal to zero.

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So if this is the case then we will just return true.

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Now if this is not the case then we proceed with the remaining part of the solution.

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So as we have discussed in the previous video, we are going to first compare the first element and

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the last element in the array which is given to us.

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So I will say const first is equal to array at index zero.

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And similarly I will say const last is equal to array at index array dot length.

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Minus one.

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Okay, so we have got the first and last element in the array which is given to us.

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Now what are the three possibilities that we have discussed in the previous video.

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The first possibility is the first element.

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And the last element may be equal.

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Okay.

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Now before we go ahead and fill the details for this, let me just over here construct the skeleton

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okay.

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So the first possibility is that the first element and the last element could be equal.

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Now if this is not the case, the other possibility is that the first element could be less than the

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last element.

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Okay.

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So that's again one more possibility.

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And if these two are not true then the remaining possibility is that the first element is larger than

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the last element okay.

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So again we don't need to write that specifically because that's the only remaining case.

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Right.

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So this means that first is larger than last.

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Now the way that we are going to approach this is that we are going to check whether the criteria needed

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for each of these cases for us to conclude that the array which is given to us is monotonic.

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So we are going to check whether that particular condition, which is the needed condition, has been

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broken.

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And if we can find that it has been broken or it has been violated, then we will just return false.

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But even after going through whichever the case is, if you are not able to return false, then we would

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come over here and we will just return true.

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Okay, so this is the skeleton of the approach.

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Now let's go ahead and fill in the details.

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If the first element and the last element are equal, we would need every element in the array to be

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equal for it to be monotonic.

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So what we are going to do is we are going to iterate from index zero till the last index of the given

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array, and we are going to check whether array at index I plus one is not equal to array at index I,

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because if that is the case, then the required condition has been violated and we will just return

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false.

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So over here I will say for let I is equal to zero, I less than array dot length minus one.

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And we have I plus plus.

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And over here I'm going to say if array at index I plus one is not equal to array at index I then we

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will just return false.

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Okay.

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So again we are checking whether the required criteria has been violated.

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And if we find that this is true we will return false.

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Okay.

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Now let's proceed.

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Now if the case is that the first element is less than the last element, then again we will have the

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same for loop.

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So we will have for let I is equal to zero I less than array dot length minus one I plus plus okay.

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And over here the needed criteria is that array at I plus one has to be greater than array at I okay.

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Because the first element is less than the last element, or the last element is greater than the first

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element.

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So we are going to check whether that criteria has been broken.

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So over here I will say if array at index I plus one.

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Is less than array at index I.

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So if this is true at any instance then we will just return false.

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Okay.

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And finally, we'll have to do something similar over here as well.

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So over here the first element is greater than the last element.

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So we would need an array at I plus one to be less than array at I.

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So we will see or we will try to check whether that criteria has been broken.

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And if we find that it's broken we will just return false.

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So again I'll say for.

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Let I is equal to zero I less than array dot length minus one.

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I plus plus.

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And over here I will say if array at index I plus one greater than array at index I.

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Then we will just return false.

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Okay, so that's it.

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Now, if we were not able to return false, then over here we'll go ahead and return true.

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Because the array which has been given to us is in fact monotonic.

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So this is the solution to the monotonic array question.

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Now let's go ahead and run this code and see if it's passing all the test cases.

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And you can see that it's passing all the test cases.

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Okay.

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And again, do make use of the user logs.

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It will help you debug your code in case you're stuck at some point.