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:
Basic 1-d dynamic programming. 
Iteration formula: a[n] = a[n-1] + a[n-2]. 
It means that you can either step from (n-1)th or (n-1)th stair to reach (n)th stair.

public class Solution {
    public int climbStairs(int n) {
        int[] A = new int[n+1];
        A[0] = 1;
        A[1] = 1;
        for(int i = 2; i <= n; i++){
            A[i] = A[i-1] + A[i-2];
        }
        return A[n];
    }
}