LADDER'S OPTIMISED APPROACH

#1

Plz refer to the comments for doubt.

#2

Hello @mverma_be19 what is the problem that you are facing?

#3

I have commented it in the code.

#4

Hello @mverma_be19 this is happening because first k terms we will not use the formula 2dp[n-1] -dp[n-k-1] because the indexing will go negative then.
that why for the first k terms we are using inly 2dp[n-1].
and we are doing 2*dp[n-1] because if i am at the 6 the step lete say and k is 3 then i have to compute for 7th step. then i know the final answer for 6 th but i have not calculated them for 7th step that for 7th steo we have to add the value fo n-1th step and subtract the n-k-1 the step value becuse that is not the size of k window and that cannot contribute now.
so we have to subtract that from the n-1 th value so that we can get total value of in between steps ans as our size of the window is k-1 now thats why we have to add n-1th value to make window of size k.
if you have any doubt you can ask here:
Happy Learning!!

#5

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