递归

1）python斐波那切数列1,1,2,3,5,8,13,21,…，编程求第n个斐波那契数列的数：

def fbql(x):
    if x == 1 or x ==2:
        return 1
    else:
        return fbql(x-1)+fbql(x-2)

2）n的阶乘（递归实现）：

def fact(n):
    if n == 0:
        return 1
    else:
        return n*fact(n-1)

number = eval(input("请输入正整数："))
result = fact(number)
print("{}的阶乘是{}".format(number,result))
##print("%d的阶乘是%d"%(number,result))

3）n的阶乘（迭代实现）:

def fact1(n):
    if n == 0:
        return 1
    else:
        result = n
        for i in range(1,n):
            result = n*i
        return result

number = eval(input("请输入正整数："))
result = fact(number)
print("{}的阶乘是{}".format(number,result))

4)n的阶乘和（用递归实现）：

def fact(n):
    if n == 0:
        return 1
    else:
        return n*fact(n-1)

number = eval(input("请输入正整数："))
sum = 0
for i in range (0,number+1):
    sum = sum + fact(i)
    print(i,fact(i),sum)
print(sum)