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?

难度系数：

容易

实现

int climbStairs(int n) {
    if (n <= 2) {
        return n;
    } else {
        int *step = new int[n+1];
        step[1] = 1;
        step[2] = 2;
        for (int i = 3; i <= n; ++i) {
            step[i] = step[i-1] + step[i-2];
        }
        int tmp = step[n];
        delete step;
        return tmp;
    }   
}