Mega Code Archive
This program uses big numbers to compute the odds of winning the grand prize in a lottery
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/*
This program is a part of the companion code for Core Java 8th ed.
(http://horstmann.com/corejava)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.math.BigInteger;
import java.util.Scanner;
/**
* This program uses big numbers to compute the odds of winning the grand prize
* in a lottery.
*
* @version 1.20 2004-02-10
* @author Cay Horstmann
*/
public class BigIntegerTest {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.print("How many numbers do you need to draw? ");
int k = in.nextInt();
System.out.print("What is the highest number you can draw? ");
int n = in.nextInt();
/*
* compute binomial coefficient n*(n-1)*(n-2)*...*(n-k+1)/(1*2*3*...*k)
*/
BigInteger lotteryOdds = BigInteger.valueOf(1);
for (int i = 1; i <= k; i++)
lotteryOdds = lotteryOdds.multiply(BigInteger.valueOf(n - i + 1)).divide(
BigInteger.valueOf(i));
System.out.println("Your odds are 1 in " + lotteryOdds + ". Good luck!");
}
}
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