解题思路：

动态规划

注意 if 判断和 for 循环

class Solution {public int climbStairs(int n) {if (n <= 2) return n;int[] dp = new int[n + 1];dp[1] = 1;dp[2] = 2;for (int i = 3; i <= n; i++) {dp[i] = dp[i - 1] + dp[i - 2];}return dp[n];}
}