LeetCode (Python): Climbing Stairs

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?

Solution:

class Solution:
    # @param n, an integer
    # @return an integer
    def climbStairs(self, n):
        before2 = 0
        before1 = 1
        for i in range(0,n):
            temp = before2 + before1
            before2 = before1
            before1 = temp
        return before1