remove typeof from choose_pivot(...)

[blackball]

It's not making any sense to use typeof(i) to define length, since 'i' is obviously a 'int'. And it's probably not a good idea to put the choose pivot function in a separate file, this will force user to call srand() unnaturally.

[xtaci]

./include/quick_sort.h: int pivot_idx = choose_pivot(begin,end);
./include/random_select.h: int pivot_idx = choose_pivot(begin,end);

it seems putting the choose_pivot function in both quick_sort & random_select is a good idea?

[xtaci]

#define RANDOM_INIT() srand(time(NULL))
#define RANDOM_NEXT(L, R) rand() % ((R) - (L)) // gen a random integer in [L, R]

macro is good for algorithms demo, and can easily be tuned in production environment.

thanks for the advice, you can PULL REQUEST, and i will merge it.

[xtaci]

updated quick_sort & random_select using your method! thanks!