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?

Java

public class Solution {
    public int climbStairs(int n) {
        int f1 = 1;
        int f2 = 2;
        if(n == 1) {
            return f1;
        } else if(n == 2) {
            return f2;
        }
        int rst = 0;
        for(int i = 3; i <= n; i++) {
            rst = f1 + f2;
            f1 = f2;
            f2 = rst;
        }
        return rst;
    }
}