# You are climbing a stair case. It takes n steps to reach to the top.
#
# Each time you can either climb 1 or 2 steps.
# In how many distinct ways can you climb to the top?
#
# Note: Given n will be a positive integer.
DP (动态规划):
class Solution():
def climbStairs(self, n):
pre, cur = 0, 1
for _ in range(n):
pre, cur = cur, pre + cur
return cur
递归,会 Time Limit Exceeded (超时):
# Time Limit Exceeded
class Solution():
def climbStairs(self, n):
if n == 1:
return 1
if n == 2:
return 2
return self.climbStairs(n - 1) + self.climbStairs(n - 2)
if __name__ == "__main__":
assert Solution().climbStairs(2) == 2