代码随想录算法训练营-动态规划-1|509. 斐波那契数、70. 爬楼梯

509. 斐波那契数  

 1 class Solution:
 2     def fib(self, n: int) -> int:
 3         if n <= 2:
 4             return n
 5 
 6         prev1, prev2 = 0, 1
 7         for _ in range(2, n+1):
 8             sum_value = prev1 + prev2
 9             prev1, prev2 = prev2, sum_value
10         
11         return prev2

70. 爬楼梯

 1 class Solution:
 2     def climbStairs(self, n: int) -> int:
 3         if n <= 1:
 4             return n
 5         
 6         prev1, prev2 = 1, 2
 7         
 8         for _ in range(3, n + 1):
 9             curr = prev1 + prev2
10             prev1, prev2 = prev2, curr
11         
12         return prev2