def frog_jump_ways(n): if n == 1: return 1 elif n == 2: return 2 # 初始化前两个值 a, b = 1, 2 # 从第3级台阶开始计算 for _ in range(3, n + 1): a, b = b, a + b return b # 测试例子 print(frog_jump_ways(3)) # 输出应该是4