non fixed voip number

Randomly generate a fixed number of digits (for example, 8 digits), The UID that is registered as a user is stored in the database Each UID is not duplicated, But it could be 12345678,12345677. There's a way to randomly generate 8-bit numbers, Then query the database for this data, There is a rebuild in the query, None is written to the database, This is a more time-consuming way. There's no better way, su

Recently browsed the "Programmer forum" found a lot of good posts, and grew a lot of knowledge, now take one of them as an example to share the experience with you.Someone raises a question: how can I generate 100 million random numbers that don't repeat?The problem is simple, and it seems as if figuring out what random numbers are and how to generate random numbers with a computer can solve the problem.Random number, the individual understood as a ce

/*** Generate order Number** Use Uniqid to get a unique, non-repeating string based on the current number of microseconds (but his first 7 bits seem to change for a long time, so do not consider the deletion) and take its 8th to 13th place. But this string contains the English alphabet, what should I do?* Use Ord to get his ASCII code, so there's the next step: u

that certainly would not be burned.So they came to you and asked. Can do?InputThe input contains multiple test cases. The first line of the input was a single integer t (1 The first line of all case contains N and m-the number of islands and bridges in Ferry Kingdom respectively (2 OutputOn the first line of all case print k-the number of bridges that would certainly not be burned. On the second line print