题解 | #跳台阶#

/**
     * 双指针保存前面2个结果，不断更新。
     * @param target
     * @return
     */
    public static int jumpFloor(int target) {
        if (target == 0) return 0;
        if (target == 1) return 1;
        if (target == 2) return 2;
        int beforeBefore = 1;
        int before = 2;
        int cur = 3;
        for (int i = 3; i < target + 1; i++) {
            cur = before + beforeBefore;
            beforeBefore = before;
            before = cur;
        }
        return cur;
    }