Sentiment: hard top, there are a lot of answers to questions. But still rewarding, Linux and database study of very good
Seeking recurrence equation T 4T (n / 2) solution of (n) = + n is
Tn + n = 4 * (tn / 2 + n / 2) = O (n) = 4 * O (N / 2) 即 O (n) = n ^ 2
A set of N sites share a pure ALOHA channel of 30Kbps, each site 100s per output frame of a 2000bit. Test and the maximum value of N ()
Aloha utilization: 0.184 * 30000 = 5520bps 2000bit / 100s = 20 bps i.e., 5520 /20 = 276 sites
In the Linux system, a score of file permissions is 754, the following statement is wrong ().
The correct answer: B Your answer: B (right) rights owner is readable, writable, executable with the permissions of the user group is writable executable other user rights only readable for all users of the file can be read 754 corresponds to 3 user permissions: file owner, group of users with other users permission rights value of the specific role of R & lt . 4 read, read. The current user can read the contents of the file, the current user can browse the directory. W 2 Write, write. The current user can add or modify the contents of the file, the current user can delete, move, or directory within the directory file. the X- 1 the Execute, execute. The current user can execute the file, the current user can access the directory. Document owner 7: 4 + 2 + 1 to the read-write executables same user group 5: 4 + 1 can perform a read other users 4: read
