(PSEUDO-)RANDOM NUMBERS

1) use default rand() function for generating A array with 100 random integers
https://www.tutorialspoint.com/c_standard_library/c_function_rand.htm

2) what is the seed and its function (check what is srand doing), random vs. pseudorandom generators
https://linuxhint.com/rand-function-in-c-language/

3) name three application of using randomness in computer science

4) read about Middle-square method and implement it in C in two versions
(https://en.wikipedia.org/wiki/Middle-square_method)

  a) version based at math 
     Hint: use modulo division
  b) version based at string conversion
  use for instance "long long", "sprintf", "atoll", "strncpy"
https://www.w3schools.com/c/c_strings.php
https://www.tutorialspoint.com/c_standard_library/c_function_sprintf.htm
https://www.geeksforgeeks.org/atol-atoll-and-atof-functions-in-c-c/
https://cpp0x.pl/dokumentacja/standard-C/strncpy/435

Note: for implementation simplicity restrict your code to 6-digits numbers
* If you consider the task too simple, make general version that can work at any digit numbers

Extra task: count after how many iterations the cycle starts to reapeat (periodicity)

5) read about Mersenne Twister 
https://en.wikipedia.org/wiki/Mersenne_Twister

Check also:
https://en.wikipedia.org/wiki/List_of_random_number_generators
https://en.wikipedia.org/wiki/Category:Pseudorandom_number_generators

6) Unix basic stuff: 
  a) /dev/random & /dev/urandom & 'od'
https://en.wikipedia.org/wiki//dev/random
https://www.thegeekstuff.com/2012/08/od-command/

  b) /dev/shm (e.g. use 'df -h', 'df -i' commands)
https://en.wikipedia.org/wiki/Shared_memory#Support_on_Unix-like_systems 

  c) aliases and .bashrc
https://pl.wikipedia.org/wiki/Alias_(Unix)
TODO: create some aliases

  d) crontab
https://pl.wikipedia.org/wiki/Crontab
https://en.wikipedia.org/wiki/Cron
TODO: using cron write current date&time to the file located in /tmp/date_cron.log every minute (next, every odd minute, etc.) 

General conclusion:
Use rand() while implementing and testing your code, generating matrices with psuedo-numbers, etc.

HOMEWORK
"O porzadkach (anty)leksykograficznych"
https://moodle.mimuw.edu.pl/pluginfile.php/286320/mod_resource/content/1/Cwiczenia_WdI_.G1-2_16-18.10.23.pdf
https://moodle.mimuw.edu.pl/pluginfile.php/288151/mod_resource/content/2/main.c
https://moodle.mimuw.edu.pl/pluginfile.php/288152/mod_resource/content/1/main.c