用0.4.7.9和小数点组成小数,你最多能组成多少?怎么排列更快

题目

用0.4.7.9和小数点组成小数,你最多能组成多少?怎么排列更快

答案

0.4/0.7/0.9/0.47/0.49/0.497/0.479/0.74/0.79/0.749/0.794/4.07/4.09/4.079/4.709/4.097/4.7/4.9/4.907/4.79/4.97/7.04/7.09/7.049/7.094/7.409/7.904/7.4/7.9/7.49/7.94/9.04/9.07/9.047/9.074/9.407/9.704/9.47/9...