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?

Note: Given n will be a positive integer.

最简单的动态规划题了吧 应该是

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