p049.java

/* 
 * Solution to Project Euler problem 49
 * Copyright (c) Project Nayuki. All rights reserved.
 * 
 * https://www.nayuki.io/page/project-euler-solutions
 * https://github.com/nayuki/Project-Euler-solutions
 */

import java.util.Arrays;


public final class p049 implements EulerSolution {
	
	public static void main(String[] args) {
		System.out.println(new p049().run());
	}
	
	
	private static final int LIMIT = 10000;
	
	public String run() {
		boolean[] isPrime = Library.listPrimality(LIMIT - 1);
		for (int base = 1000; base < LIMIT; base++) {
			if (isPrime[base]) {
				for (int step = 1; step < LIMIT; step++) {
					int a = base + step;
					int b = a    + step;
					if (       a < LIMIT && isPrime[a] && hasSameDigits(a, base)
					        && b < LIMIT && isPrime[b] && hasSameDigits(b, base)
					        && (base != 1487 || a != 4817))
						return "" + base + a + b;
				}
			}
		}
		throw new RuntimeException("Not found");
	}
	
	
	private static boolean hasSameDigits(int x, int y) {
		char[] xdigits = Integer.toString(x).toCharArray();
		char[] ydigits = Integer.toString(y).toCharArray();
		Arrays.sort(xdigits);
		Arrays.sort(ydigits);
		return Arrays.equals(xdigits, ydigits);
	}
	
}