Incereasing decreasing sequence

[shashank_sabharwal]

please explain the challenge in detail,
,
with input and output, and also give me a hint to solve this

[Ishitagambhir]

hi @shashank_sabharwal
you will be given some numbers, you have to tell whether the sequence can be divided into 2 parts such that the first part is strictly decreasing and the second part is strictly increasing or not.
In this example the sequence is 1 2 3 4 5
so we can see that it can be divided into such a sequence. The first part is empty, and the second part is strictly increasing
Another example is
5 4 3 4 5

[shashank_sabharwal]

@Ishita . please share the solution of increasing decreasing sequence

[Ishitagambhir]

@shashank_sabharwal please try to write the code on your own first, i’ll help you if you are stuck anywhere

[shashank_sabharwal]

@ Ishita . kind help me as soon as possible thank you

[Ishitagambhir]

hi @shashank_sabharwal
so you have to check 2 things, whether the array is increasing/decreasing
but you need to know when to check which one
so you can try to keep a boolean variable, whose value will indicate whether to check inc/dec

[shashank_sabharwal]

@Ishita sorry but i am not getting this question , is there any hint video or article related to solve this question, you are asking to use a boolean variable but i dont even know the way to write my code , where to use boolean variable how my boolean variable will updated and in which loop?? how i go through my array linearly ,totally blanked in this challenge

[Ishitagambhir]

hi @shashank_sabharwal dont worry! it may seem hard in the beginning, just be patient.
Try to go through this approach once, and let me know if there’s anything you did not understand. Once you have completely understood the approach, try to code it out step by step. Dont worry about getting it correct in one go! The flag variable being mentioned below is the boolean variable I suggested using.

@Kartikkhariwal1

First we assume that our sequence is decreasing only. We also assume that our sequence is initially valid and only try to disprove it during the course.
We compare our current element with the previous element and based on that comparison make our decision.
If the curr element is equal to the prev element , we see that the sequence is neither strictly increasing or decreasing so we mark our sequence as invalid.
If the curr element is greater than the prev element, then we realise that the sequence has started increasing and we mark it so using a flag variable “goingUp” which we had initially marked as false based on our assumption that the sequence is decreasing.
If the curr element is less than the previous element and the current sequence is also proceeding as decreasing , we are to do nothing. However if the current sequence is increasing and we get a pair for a decreasing sequence then we mark our sequence as invalid since we cannot have a decreasing part after the increasing sequence.

[shashank_sabharwal]

i totally understand the question but how to implement this i don’t want to give up ,

[shashank_sabharwal]

i am not able to code this approach ,

[Ishitagambhir]

hi @shashank_sabharwal worry not! give it another try. Dont try to write the whole code in one go, start small. Even if you can write the code to just check whether its stricly decreasing first, write only that much. I’ll help you in making changes in that step by step.