题解 | #斐波那契数列#

public class Solution {
    public int Fibonacci(int n) {
        if (n == 1 || n == 2) return 1;
//        return Fibonacci(n - 2) + Fibonacci(n - 1);
        int sum1 = 1;
        int sum2 = 1;
        for (int i = 3; i <= n; i++) {
            sum2 = sum1 + sum2;
            sum1 = sum2 - sum1;
        }
        return sum2;
    }
}