You are climbing a staircase. It takes n
steps to reach the top.
Each time you can either climb 1
or 2
steps. In how many distinct ways can you climb to the top?
Example 1:
Input: n = 2
Output: 2
Explanation: There are two ways to climb to the top.
- 1 step + 1 step
- 2 steps
Example 2:
Input: n = 3
Output: 3
Explanation: There are three ways to climb to the top.
- 1 step + 1 step + 1 step
- 1 step + 2 steps
- 2 steps + 1 step
Constraints:
-
1 <= n <= 45
SOLUTION:
class Solution:
def climbStairs(self, n: int) -> int:
a = 1
b = 2
if n == 1:
return a
if n == 2:
return b
for _ in range(n - 2):
a, b = b, a + b
return b
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