[7] wins the offer. Fibonacci number [by Python]

Title Description

We all know that Fibonacci number, and now asked to enter an integer n, you export item n Fibonacci Fibonacci number sequence.

n<=39

method 1:

cycle.

       
       
# -*- coding:utf-8 -*-
class Solution:
def Fibonacci(self, n):
# write code here
if n <= 2:
return [ 0, 1, 1][n]
first, second = 1, 1
while n > 2:
first, second = second, first + second
n -= 1
return second
       
       

Running time: 25ms

Take up memory: 5728k

Method 2:

Recursion.

       
       
# -*- coding:utf-8 -*-
class Solution:
def Fibonacci(self, n):
# write code here
if n == 0:
return 0
Elif N == 1 :
return 1
else:
return self.Fibonacci(n - 1) + self.Fibonacci(n - 2)
       
       

Fail

Your code has been saved
run timeout: Your program failed to run at the end of the specified time, check to see if there is wrong or cycle through the large complex algorithms.
case was 0.00% by

Obviously, when implemented using a recursive method, time and space complexity of the complex is too big. Since the function calls itself, but a function call is time and space consumption: every function call, you need the memory stack space allocated to save the parameters, return address and temporary variables, and to the stack pressed into data and pop-up data needs time.

Title Description

We all know that Fibonacci number, and now asked to enter an integer n, you export item n Fibonacci Fibonacci number sequence.

n<=39

method 1:

cycle.

    
    
# -*- coding:utf-8 -*-
class Solution:
def Fibonacci(self, n):
# write code here
if n <= 2:
return [ 0, 1, 1][n]
first, second = 1, 1
while n > 2:
first, second = second, first + second
n -= 1
return second
    
    

Running time: 25ms

Take up memory: 5728k

Method 2:

Recursion.

    
    
# -*- coding:utf-8 -*-
class Solution:
def Fibonacci(self, n):
# write code here
if n == 0:
return 0
Elif N == 1 :
return 1
else:
return self.Fibonacci(n - 1) + self.Fibonacci(n - 2)
    
    

Fail

Your code has been saved
run timeout: Your program failed to run at the end of the specified time, check to see if there is wrong or cycle through the large complex algorithms.
case was 0.00% by

Obviously, when implemented using a recursive method, time and space complexity of the complex is too big. Since the function calls itself, but a function call is time and space consumption: every function call, you need the memory stack space allocated to save the parameters, return address and temporary variables, and to the stack pressed into data and pop-up data needs time.