Leetcode 70 Climbing Stairs

class Solution:
    # @param {integer} n
    # @return {integer}
    def climbStairs(self, n):
        dp = [0, 1, 2]
        i = 3
        while i <= n:
            dp.append(dp[i-1] + dp[i-2])
            i += 1
        return dp[n]

class Solution:
    # @param {integer} n
    # @return {integer}
    def climbStairs(self, n):
        dp = [1]*(n + 1)
        for i in range(2, n + 1):
            dp[i] = dp[i-1] + dp[i-2]
        return dp[n]