第七章第5讲：python函数的递归

# n的阶层
def calculate(n):
    result = n
    for i in range(1,n): # 1<=i<n
        result *= i
    return result
print(calculate(4))

# 优化后的递归
def factorial(n):
    if n == 1:
        return 1
    else:
        return n * factorial(n-1)
print(factorial(4))

# 如下递归持续运行至崩溃
def fibs():
    return fibs()
fibs()