leetcode 70 Climbing Stairs（难易度：Easy）

Climbing Stairs

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?

代码：

int climbStairs(int n) {    if(n == 0 || n == 1 || n == 2)        return n;    int a = 2;    int b = 1;    int res = 0;    for(int i = 3; i <= n; i++)    {        res = a + b;        b = a;        a = res;    }    return res;}

原题地址：https://leetcode.com/problems/climbing-stairs/