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?

题目	Climbing Stairs
通过率	34.1%
难度	Easy

题目是经典的上台阶问题，可以抽象成著名的Fibonacci数列。

java代码：

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;
    }
}