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