03.斐波那契数列

public class Solution {
    public int Fibonacci(int n) {
        if(n <= 1) return n;
        int a = 0;
        int b = 1;
        int c = 0;
        for(int i = 2; i <=n ;i++){
            c = a + b;
            a = b;
            b = c;
        }
        return c;
    }
}