Python - Recursion（factorial、reverse、fibonacci、hanoi）

def factorial(n):
    if n<=1:
        return 1
    else:
        return factorial(n-1)*n

if __name__ == "__main__":
    print(factorial(3))

 

def Reverse(n):
    '''
    n is a number
    '''
    print(n%10,end='')
    if n>10:
        return Reverse(n//10)
    
if __name__ == "__main__":
    Reverse(12345)


#--------------------------------------------------------------------------


def Closure(n):
    result = []
    def Reverse(n):
        '''n is a number'''
        result.append(n%10)
        if n>10:
            return Reverse(n//10)
        return result
    return Reverse
    
if __name__ == "__main__":
    data = 1234567
    Reverse = Closure(data)
    result = Reverse(data)
    reverse_data = 0
    for i,j in enumerate(result):
        reverse_data += j*(10**(len(result)-i-1))
    print(reverse_data)

 

#需求：输入n(Index)，输出fibonacci的第n个数据

def fibonacci_recursion(n):
    if n<2:
        return 1
    else:
        return fibonacci_recursion(n-1)+fibonacci_recursion(n-2)

def fibonacci(n):
    f1 = f2 = 1
    for i in range(1,n):
        f1,f2 = f2,f1+f2
    return f2
    
if __name__ == "__main__":
    print("fibonacci[%d] = %d" % (10,fibonacci_recursion(10)))
    print("fibonacci[%d] = %d" % (20,fibonacci(20)))

 

def hanoi(n,x,y,z):
    if n==1:
        print(n,':',x,"->",z)
    else:
        hanoi(n-1,x,z,y)
        print(n,':',x,"->",z)
        hanoi(n-1,y,x,z)

if __name__ == "__main__":
    hanoi(3,'A','B','C')