But sir how can we use dp

#1

as here is no overlapping subproblems than how can we use dp??

#2

say we want to find string of len(N)
Now if we form recursive solution then its like that (Assume string as function with 2 args len and ending number)
then String(n)=string(n,end 0) + string(n,end 1)
string(n,end 0) =string(n-1,end 0) + string(n-1,end 1)
string(n,end 1) =string(n-1 end 0)

Here see 2 calls to string(n-1 end 0)
This is overlapping subproblem ,now if u expand the tree ,u will see many overlapping subcalls