【DP】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?

public class Solution {    public int climbStairs(int n) {        int one = 1;        int two = 2;                if(n == 1) return 1;        else if(n == 2) return 2;                for(int i=3; i<=n; i++){            int t = one + two;            one = two;            two = t;        }        return two;    }}