5     - оутпут   3
10    - оутпут   4
0 (return)

Got to do only one thing
find the maximum in this array
If the array size is 5 then maximum = 3
and if 10 then 4 is max
so, I solved the problem
in the givven way
and in given way the max of 5(sized array) isn't 3
here is the input and output

cin>> 5
0    1    1    2    1
max = 2
_____________________________
cin >> 10
0    1    1    2    1    3    2    3    1    4
max = 4

_______________________________________
input>>6
0    1    1    2    1    3
max = 3
______________________________________


please
help
the Solution of Problem is Actually thiS, In c++ But dOesn't
work maybe you can notice  something??

for(int i = 0; i < a; i++){
        if(2*i < a){
            arr[2*i] = arr[i];
        }
        if(2*i+1 < a){
            arr[2*i+1] = arr[i] + arr[i+1];
        }
    }

OK
already got it