24Point

import java.util.HashSet;

public class Game24Point {
	private static int n = 4;
	private static int size = (int) Math.pow(2, n);
	private static HashSet<Double>[] S = new HashSet[size];
	private static double[] array = { 5, 5, 5, 1 };
	private static double targetNum = 576;

	private static boolean useFactorial = true;

	private static void init() {
		for (int i = 0; i < size; i++) {
			S[i] = null;
		}
		for (int i = 0; i < n; i++) {
			int temp = (int) Math.pow(2, i);
			S[temp] = new HashSet<Double>();
			S[temp].add(array[i]);
			if (useFactorial) {
				S[temp].add(new Double(factorial((int) array[i])));
			}
		}
		for (int i = 0; i < size; i++) {
			S[i] = f(i);
		}
		Check(S[(int) Math.pow(2, n) - 1]);
	}

	private static void Check(HashSet<Double> arrayList) {
		for (Double temp : arrayList) {
			if (Math.abs(temp - targetNum) < 1E-6) {
				System.out.println("Succeed");
			}
		}

	}

	private static HashSet<Double> f(int i) {
		if (S[i] != null) {
			return S[i];
		}
		S[i] = new HashSet<Double>();
		for (int x = 1; x < i; x++) {
			if ((x & i) == x) {
				for (Double temp : Fork(f(x), f(i - x))) {
					S[i].add(temp);
					// if (useFactorial) {
					// if (Math.abs(temp - (int) temp.doubleValue()) < 1E-6
					// && temp > 0) {
					// S[i].add(new Double(factorial((int) temp
					// .doubleValue())));
					// }
					// }
				}
			}
		}
		return S[i];
	}

	private static HashSet<Double> Fork(HashSet<Double> hashSet,
			HashSet<Double> hashSet2) {
		HashSet<Double> ret = new HashSet<Double>();
		for (Double a : hashSet) {
			for (Double b : hashSet2) {
				ret.add(a + b);
				ret.add(a - b);
				ret.add(b - a);
				ret.add(a * b);
				if (b != 0) {
					ret.add(a / b);
				}
				if (a != 0) {
					ret.add(b / a);
				}
			}
		}
		return ret;
	}

	private static int factorial(int x) {
		if (x < 0) {
			throw new IllegalArgumentException("x must be>=0");
		}
		int fact = 1;
		for (int i = 2; i <= x; i++) {
			fact *= i;
		}
		return fact;
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		init();

	}

}