70. Climbing Stairs

题目来源【Leetcode】

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.

这道题比较简单，直接上代码：

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