joriki’s gists

joriki / Question4882568.java

Created March 18, 2024 10:57

Count the schedules for round-robin tournaments; see https://math.stackexchange.com/questions/4882568

	import java.util.BitSet;

	public class Question4882568 {
	static boolean [] [] played;
	static int count;
	static int n;

	public static void main (String [] args) {
	for (n = 2;;n += 2) {
	count = 0;

joriki / Question4859023.java

Created February 8, 2024 08:26

Estimate the probability of a certain inequality being satisfied for uniformly distributed random variables; see https://math.stackexchange.com/questions/4859023.

	public class Question4859023 {
	final static long ntrials = 100000000L;

	public static void main(String [] args) {
	long count = 0;

	for (long n = 0;n < ntrials;n++) {
	double x1 = 5 * Math.random();
	double x2 = 5 * Math.random();
	double y1 = 5 * Math.random();

joriki / Question4849448.java

Created January 23, 2024 14:21

Compute the value of a game of placing non-attacking kings on an n x n board; see https://math.stackexchange.com/questions/4849448.

	import java.util.HashMap;
	import java.util.Map;

	public class Question4849448 {
	final static int d = 8;
	final static int n = d * d;

	static long [] moves = new long [n];
	static long [] [] transformedMoves = new long [n] [8];

joriki / Question4840933.java

Last active January 11, 2024 08:52

Estimate the probability that the triangle formed by three uniformly random points on the sphere contains its circumcentre; see https://math.stackexchange.com/questions/4842652.

	public class Question4840933 {
	final static long ntrials = 2000000;

	public static void main(String [] args) {
	double [] [] x = new double [3] [3];
	double [] c = new double [3];

	long count = 0;

	for (long n = 0;n < ntrials;n++) {

joriki / OEISScanner.java

Created December 28, 2023 23:04

find palindromic U-shaped triangular arrays in OEIS; see https://math.stackexchange.com/questions/4835012

	import java.io.BufferedReader;
	import java.io.FileReader;
	import java.io.IOException;
	import java.math.BigInteger;

	public class OEISScanner {
	public static void main (String [] args) throws IOException {
	// OEIS sequence data downloaded from https://oeis.org/stripped.gz
	BufferedReader reader = new BufferedReader (new FileReader (args [0]));

joriki / Question4636935.java

Created February 11, 2023 08:43

Simulate an urn where two balls of the colour drawn are added after each draw; see https://math.stackexchange.com/questions/4636935.

	package info.joriki.math.stackexchange;

	public class Question4636935 {
	final static int ntrials = 10000;
	public static void main(String [] args) {
	int count = 0;
	int total = 0;

	for (int n = 0;n < ntrials;n++) {
	int nblack = 1;

joriki / Question4631555.java

Created February 6, 2023 12:54

Generate an orthogonal matrix and a corresponding vector that satisfy certain constraints; see https://math.stackexchange.com/questions/4631555.

	import java.util.Arrays;
	import java.util.Random;

	public class Question4631555 {
	final static int l = 4;
	final static int n = (l * (l - 1)) / 2;

	final static Random random = new Random();

	public static void main(String [] args) {

joriki / Question4629747.java

Created February 1, 2023 03:05

Maximize the score in a game where boxes are removed according to the sum of two dice; see https://math.stackexchange.com/questions/4629747.

	package info.joriki.math.stackexchange;

	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;

	import info.joriki.math.algebra.BigRational;

	public class Question4629747 {

joriki / Question4624075.java

Created January 25, 2023 15:11

Find bit strings with no pairwise XOR sums in common; see https://math.stackexchange.com/questions/4624075.

	import java.util.Random;

	public class Question4624075 {
	final static int k = 34;
	final static int n = 10;
	final static int m = 1 << n;
	final static int nvalues = (k * (k + 1)) / 2;

	final static Random random = new Random();

joriki / Question4622699.java

Last active March 29, 2024 20:55

Place party guests at dinner tables so they all meet each other; see https://math.stackexchange.com/questions/4622699.

	import java.util.Random;

	public class Question4622699 {
	final static int nrounds = 7;
	final static int ntables = 5;
	final static int nchairs = 4;
	final static int npeople = ntables * nchairs;

	final static Random random = new Random();

Felix Pahl joriki