Exercise: http://www.crypto-world.com/lcg_value.html
Usage:
[master][~/projects/lcg_value]$ make && ./lcg-state-forward 2982398 43523 100
gcc -g lcg-state-forward.c -o lcg-state-forward
gcc -g lcg-state-forward-orig-with-modification.c -o lcg-state-forward-orig-with-modification
Found initial states of s1=2982398 s2=43523!