题解 | 牛牛学数列5

import java.util.Scanner;
//后位等于前两位之和
// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();//项数
        if (a == 1 || a == 2) {
            System.out.print("1");
        }

        else {
            int sum, x1 = 1;
            int cup, x2 = 1;

        for (int i = 3; i <= a ; i++) {
            cup = x1;
            x1 = x1 + x2;
            x2 = cup;
        }
        System.out.print(x1);
        }
    }
}