count=0
def fn(n,begin,end,middle):global count   #global更新并以字典形式返回当前全部局部变量(如果不是全局变量在每次调用时初值会被清零)if n==1:print("{}:{}-->{}".format(1,begin,end))count+=1else :fn(n-1,begin,middle,end)print("{}:{}-->{}".format(n,begin,end))count+=1fn(n-1, middle,end,begin)
fn(3,"A","C","B")
print("执行的次数为{}次".format(count))