[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?

简单的dp 问题，用填表法解决：

public int climbStairs(int n) {
int[] res = new int[n + 1];//res[i]表示爬i阶楼梯的所有可能性
res[0] = 1;
res[1] = 1;

for (int i = 2; i <= n; i++){
res[i] = res[i - 1] + res[i - 2];
}
return res
;
}

用递归会超时