On Fibonacci sequence

Fibonacci Sequence definition

F[ 0 ] = 0;
F[ 1 ] = 1;
F[ i ] = F[ i - 1] + F[ i - 2]; （i > 1）

seek Fibonacci The second in a series n Number

1. The first time complexity O(n)
2. Second time complexity O(2^n)

    public static int getFibo(int n){ 
    
        int first = 0;
        int second = 1