joriki’s gists

joriki / CospectralGraphs.java

Created February 8, 2012 07:22

Find all cospectral connected graphs on n vertices

	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.HashMap;
	import java.util.HashSet;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Map;
	import java.util.NoSuchElementException;
	import java.util.Set;
	import java.util.Stack;

joriki / Question107694.java

Created February 10, 2012 09:28

code for math.stackexchange question 107694 (http://math.stackexchange.com/a/107784): does division allow shorter arithmetic expressions with single digits as operands?

	import java.util.Map;
	import java.util.TreeMap;

	public class Question107694 {
	final static int n = 7;

	static boolean handle (Map<Integer,String> newExpressions,String ej,String ek,int result,char op) {
	boolean isNew = !newExpressions.containsKey (result);
	if (isNew)
	newExpressions.put (result,"(" + ej + ")" + op + "(" + ek + ")");

joriki / Question118794a.java

Created March 11, 2012 15:03

Determine the number of transitions between conjugacy classes induced by scrambling three elements

	// This version counts the transitions by tallying the different ways in which the scrambling can rearrange the cycles

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

	class Partition {
	List<Integer> parts = new ArrayList<Integer> ();

joriki / Question118566.java

Created March 15, 2012 15:53

Brownian Backgammon simulation to test doubling strategies

	import java.util.Random;

	public class Question118566 {
	public static void main (String [] args) {
	double lambda0 = Double.parseDouble (args [0]);
	double k0 = Double.parseDouble (args [1]);
	double lambda1 = Double.parseDouble (args [2]);
	double k1 = Double.parseDouble (args [3]);

	int ntrials = 100000;

joriki / Question129580.java

Created April 10, 2012 08:31

Code to count card combinations according to this math.SE question: http://math.stackexchange.com/questions/129580

	import java.util.ArrayList;
	import java.util.List;

	public class Question129580 {
	static List<int []> getPermutations (int n) {
	return getPermutations (n,n);
	}

	static List<int []> getPermutations (int n,int k) {
	List<int []> permutations = new ArrayList<int[]> ();

joriki / Question130758.java

Created April 12, 2012 07:21

Count the number of tilings of an n by n square with n rectangles of integer sides and area n

	// Count the number of tilings of an n by n square with n rectangles of integer sides and area n
	// See http://math.stackexchange.com/questions/130758

	public class Question130758 {
	final static int maxn = 100;

	static int n;
	static int [] divisors = new int [maxn];
	static int ndivisors;
	static boolean [] [] grid;

joriki / Question132847.java

Created April 17, 2012 18:45

Count the number of words over an alphabet of n letters without non-overlapping repeated strings of length 2

	import java.util.Set;
	import java.util.HashSet;

	public class Question132847 {
	static int n;
	static int count;

	static Set<String> pairs = new HashSet<String> ();

	public static void main (String [] args) {

joriki / Question33227.java

Created May 13, 2012 23:27

Find the optimal strategy in a variant of the best choice problem where the median is to be selected; see http://math.stackexchange.com/questions/33227

	import java.util.Random;

	public class Question33227 {
	public static void main (String [] args) {
	int n = Integer.parseInt (args [0]);
	int n2 = n / 2;

	int [] d = new int [n];
	for (int i = 0;i < d.length;i++)
	d [i] = -1;

joriki / Question177465.java

Created August 1, 2012 09:34

Search for common multiples of Voyager polynomials with few monomials: http://math.stackexchange.com/questions/177465

	import java.util.BitSet;

	public class Question177465 {
	static BitSet [] bits = {new BitSet (),new BitSet ()};
	static int [] polynomials = {Integer.parseInt ("1011011",2),Integer.parseInt ("1111001",2)};

	public static void main (String [] args) {
	bits [0] = new BitSet ();
	bits [1] = new BitSet ();

joriki / Question176383.java

Created August 7, 2012 10:37

simulate raindrops covering a table; see http://math.stackexchange.com/questions/176383

	import java.util.List;
	import java.util.ArrayList;
	import java.util.Random;

	public class Question176383 {
	public final static Centre origin = new Centre (0,0);

	static List<Centre> centres = new ArrayList<Centre> ();

	static enum Ternary {

Felix Pahl joriki