数楼梯 Java
import java.util.*;import java.math.*;public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();System.out.println(solve(n));}static String solve(int n) {if (n <= 2) return n + \"\"; // 1级台阶1种方法，2级台阶2种方法 BigInteger a = BigInteger.ONE; // long会爆，用高精度 BigInteger b = new BigInteger(\"2\"); // 斐波那契for (int i = 3; i <= n; i++) {BigInteger c = a.add(b);a = b;b = c;}return b.toString();}}~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
