How to manually generate random numbers [closed]

Answer 1

The Mersenne twister has a very long period (2^19937-1).

Here's a very basic implementation in C++:

struct MT{
    unsigned int *mt, k, g;
    ~MT(){ delete mt; }
    MT(unsigned int seed) : mt(new unsigned int[624]), k(0), g(0){
        for (int i=0; i<624; i++)
            mt[i]=!i?seed:(1812433253U*(mt[i-1]^(mt[i-1]>>30))+i);
    }
    unsigned int operator()(){
        unsigned int q=(mt[k]&0x80000000U)|(mt[(k+1)%624]&0x7fffffffU);
        mt[k]=mt[(k+397)%624]^(q>>1)^((q&1)?0x9908b0dfU:0);
        unsigned int y = mt[k];
        y ^= (y >> 11);
        y ^= (y << 7) & 0x9d2c5680U;
        y ^= (y << 15) & 0xefc60000U;
        y ^= (y >> 18);
        k = (k+1)%624;
        return y;
    }
};

Answer 2

If you are wanting to manually, hard code, your own random generator I can't give you efficiency, however, I can give you reliability. I actually decided to write some code using time to test a computer's processing speed by counting in time and that turned into me writing my own random number generator using the counting algorithm for modulo (the count is random). Please, try it for yourselves and test on number distributions within a large test-set. By the way, this is written in python.

def count_in_time(n):
   import time
   count = 0
   start_time = time.clock()
   end_time = start_time + n
   while start_time < end_time:
       count += 1
       start_time += (time.clock() - start_time)
   return count


def generate_random(time_to_count, range_nums, rand_lst_size):
    randoms = []
    iterables = range(range_nums)
    count = 0
    for i in range(rand_lst_size):
        count += count_in_time(time_to_count)
        randoms.append(iterables[count%len(iterables)])
    return randoms