1.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?

2.解决方案

class Solution {
public:
    int climbStairs(int n) {
        if (n == 0 || n == 1) return 1;  
        int prev = 1;  
        int current = 1;  
        for (int i = 2; i <= n; i++) {  
            int temp = current + prev;  
            prev = current;  
            current = temp;  
        }  
        return current;
    }
};

思路：这个就是跟​​斐波那契数列​​一样的解法。用递归就太慢了。

​​http://www.waitingfy.com/archives/1602​​