LeetCode Climbing Stairs

题目

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?

 

到第i格的路线数n(i)=n(i-1)+n(i-2)，由此递推即可。

 

代码：

class Solution {public:    int climbStairs(int n) {        if(n<3)return n;int nw1=1,nw2=2,nw;//到当前格前两格的路线数，前一个的路线数，当前格的路线数for(int i=3;i<=n;i++){nw=nw1+nw2;nw1=nw2;nw2=nw;}return nw;    }};