1 def go_upstairs(n):
 2     if(n == 0):
 3         return 0
 4     elif(n == 1):
 5         return 1
 6     elif(n == 2):
 7         return 2
 8     elif(n == 3):
 9         return 4
10     elif(n > 3):
11         return go_upstairs(n - 1) + go_upstairs(n - 2) + go_upstairs(n - 3)
12 
13 number_of_steps = 6#楼梯阶数
14 print("%d级阶梯，有%d中上楼方法"%(number_of_steps, go_upstairs(number_of_steps)))

6级阶梯，有24中上楼方法

Process finished with exit code 0