LeetCode-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?

这道题可以用 recursive或者DP做，但是recursive 的效率太低了。

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