Max length bitonic subarray

#1

pls explain the question

#2

Hello @vashishthkuntal.gajjar2019
please read this all:
consider an index i .

if u know longest increasing sequence thats ends at i and longest decreasing sequence that starts from i then finding bitonnic sequence with i as pivot will be easy right?

it l1 is length of longest increasing sequence ending at i.
if l2 is length of longest decreasing sequence starting from i
then bitonnic length with pivot i will be l1 + l2 -1 (-1 becuase we have consider i in both the sequence )

now if we repeat this process for all values of i { 0 … n-1 } and pick maximum of all it will be our answer right?

how to construct increasing / decreasing array?
if u r at index i then u can add it to sequence ending at index i-1 only when a[i] > a[i-1] right ? becuase then only the sequnce will be increasing.
so in that case increasing[i]= 1+ increasing[i-1]
this is what they are doing

same logic holds for decreasing array

if you have any doubt you can ask here:
Happy Learning!!

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#3

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