代码如下:
times = 0def test(num,a,b,c): globaltimes ifnum==1: print (a,b) times+=1
else: test(num-1,a,c,b) test(1,a,b,c) test(num-1,c,b,a)
test(12,"a","b","c")print "经过的步数passing：%d"%times
