[leetcode]Climbing Stairs

秒杀，斐波那契数列。而且，其实不用像我的答案那也开数组的，用几个变量存就行了。

public class Solution {

    public int climbStairs(int n) {

        // Start typing your Java solution below

        // DO NOT write main() function

        if (n == 0) return 0;

        if (n == 1) return 1;

        if (n == 2) return 2;

        int m[] = new int[n+1];

        m[1] = 1;

        m[2] = 2;

        for (int i = 3; i <=n; i++) {

            m[i] = m[i-1] + m[i-2];

        }

        return m[n];

    }

}