1 递归式
#递归实现阶乘
def jc1(kin):
if (kin == 0 or kin == 1):
return 1
return kin * jc1(kin - 1)
2 循环式
#循环实现阶乘和
def jc(x):
# sum=0
# while(x>0):
num = 1
for i in range(1,x+1):
num*=i
# sum+=gg
# x=x-1
return num
调用:
def pl(x,y):
res=1
# if(x-y>y):
# for i in range(x,y+1,-1):
# res*=jc1(i)/jc1(x-i+1)
return jc(x)//jc(x-y)
结果:
print("结果有:{0} 种".format(pl(6,4)))
#结果有:360 种