java - Trying to achieve a simple algorithm -

java - Trying to achieve a simple algorithm -

i have n options, between 1 , thousands. example, explain 3 options, need algorithm work n options.

a=30% possibilities b=50% possibilities c=20% possibilities

i need randomly 1 of these 3 options, according probabilities.

i achieved generating random number between 0 , 100, , i'm doing heavy , ugly code know when number between 0 , possibilities number, between possibilities , b possibilities, etc.

do know improve way this?

choose random number in range need, start subtracting probability of each alternative number until reach 0. lastly probability subtracted want.

int[] possibilities = new int[] {20,50,30}; random rand = new random(); int r = rand.nextint(100); int = 0; (i=0;i<possibilities.length; i++) { r -= possibilities[i]; if (r <= 0) break; } system.out.println(i); // index of possibility

java c algorithm