Doubt regarding count number of binary strings problem

#1

How to solve this question using Top Down DP ? Can you explain me the Top Down DP algorithm ?

#2

Hey @Lalit2142
BinryCount(n)= BinryCount(n - 1) +BinryCount(n - 2)
Base Case
if (n == 0 || n == 1) {
return n+1;
}