leetcode----------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?

題目	Climbing Stairs
經過率	34.1%
難度	Easy

題目是經典的上臺階問題，能夠抽象成著名的Fibonacci數列。

java代碼：

public class Solution {
    public int climbStairs(int n) {
        if(n<0) return 0;
        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;
    }
}