[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];
    }
}