动态规划之爬楼梯（二）
class Solution {
public:int climbStairs(int n) {if (n <= 1) return n;vector<int> dp(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];}
};
class Solution {
public:int climbStairs(int n) {if (n <= 1) return n;vector<int> dp(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];}
};