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.

 

Example 1:

Input: 2Output:  2Explanation:  There are two ways to climb to the top.1. 1 step + 1 step2. 2 steps

 

Example 2:

Input: 3Output:  3Explanation:  There are three ways to climb to the top.1. 1 step + 1 step + 1 step2. 1 step + 2 steps3. 2 steps + 1 step 这个一道基本动态规划题目，做动态规划题目有四个步骤： 1）确定原问题和子问题 2）确定状态 3）确认边界状态的值 4）确定状态转移方程

1 #include 
     
       2  3 #include 
      
        4 class Solution { 5 public: 6     int climbStairs(int n) { 7         std::vector
       
         dp(n + 3, 0); 8         dp[1] = 1; 9         dp[2] = 2;10         for (int i = 3; i <= n; i++){11             dp[i] = dp[i-1] + dp[i-2];12         }13         return dp[n];14     }15 };16 17 int main(){18     Solution solve;19     printf("%d\n", solve.climbStairs(3));    20     return 0;21 }