Can you explain this part of code given in editorial?

#1

Step 3) Find the length of maximum length bitonic sequence
max = inc[0] + dec[0] - 1;
for (i = 1; i < n; i++)
if (inc[i] + dec[i] - 1 > max)
max = inc[i] + dec[i] - 1;

max = inc[0] + dec[0] - 1;//What are we calculating in this step?

#2

Hey @isingh
We are not calculating anything there ,we are just setting it for reference to other values u can start with max =0 and traverse the whole array from 0 to n-1

If you are making the meaning of Inc(i)+dec(i) -1
then inc(i) has the length of max increasing array till ith index and dec(i) has the length of max decreasing array from ith index
so we take sum of both which gives us bitonic subarray and -1 is because ith element is included in both

#3

Eg
1 6 8 9 3 4 6 5
inc array
1 2 3 4 1 2 3 1
dec array
1 1 1 2 1 1 1 2
max(1+1-1,2+1-1,3+1-1,…)
Ans 4 + 2 -1

#4

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