補充kelly

拿到2顆紅球的機率與黑球相等,故500/2001*2=1000/2001
拿兩顆相異情形,只須考慮第2顆相異即可,機率是
1001/2001
即m=2C(1001,2)/C(2002,2)=1000/2001
N=1-M=1001/2001