用两种方法（递归和DP）实现了青蛙跳台阶

int jumpFloor2(int number) {
        if (number < 0) return 0;
        if (number < 2) return 1;
        return jumpFloor(number-1) + jumpFloor(number-2);
    }

int jumpFloor2(int number) {
        if (number < 0) return 0;
        if (number < 2) return 1;
        int jump2 = 1;
        int jump1 = 1;
        for (int i=2; i<=number; i++) {
            int tmp = jump2 + jump1;
            jump2 = jump1;
            jump1 = tmp;
        }
        return jump1;
    }