# 1.Recursion slow
def fibonacci_recursion(n):
if n <= 1:
return n
else:
return fibonacci_recursion(n-1) + fibonacci_recursion(n-2)
# 2.List save every value, avoid repeate compute fast
def fibonacci_list(n):
F =[0,1]
if n<=1 :
return n
else:
for i in range(2,n+1):
F.append(F[i-1] + F[i-2])#soul
return F[n]
# 3.1 for loop, update a and b,don't need List, increase space efficiency and reduce time complexity O(n)
def fibonacci_forloop_update(n):
if n<=1 :
return n
else:
a,b = 0,1
for _ in range(2,n+1):
a,b = b,a+b
return b
# 3.2 while loop, update a and b,don't need List, increase space efficiency and reduce time complexity O(n)
def fibonacci_whileloop_update(n):
if n<=1 :
return n
else:
a,b = 0,1
i = 2
while i <= n:
a,b = b,a+b
i+=1
return b
for i in range(100):
# print(fibonacci_list(i))
# print(fibonacci_recursion(i))
# print(fibonacci_forloop_update(i))
print(fibonacci_whileloop_update(i))About Fibonacci formula: https://www.zhihu.com/question/25217301
标签：About,slow,recursion,question,www,Fibonacci From： https://www.cnblogs.com/millionyh/p/18101310