Traverser.java

package com.karthik.glosfer;

import java.security.NoSuchAlgorithmException;
import java.util.HashSet;
import java.util.Set;

public class Traverser {

	static int totalPoints = 0;
	static int rejectCount = 0;
	static Set<String> hashes = new HashSet<String>();

	public static void main(String[] args) throws NoSuchAlgorithmException {

		int min = Integer.MIN_VALUE;
		int max = Integer.MAX_VALUE;
		move(0, 0, min, max);
		System.out.println("Total number of points reached: " + totalPoints);
		System.out.println("total number of rejected points:" + rejectCount);
	}

	private static void move(int x, int y, int min, int max) throws NoSuchAlgorithmException {
		// Top
		findPath(x, y - 1, min, max);
		// RIGHT
		findPath(x + 1, y, min, max);
		// Down
		findPath(x, y + 1, min, max);
		// Left
		findPath(x - 1, y, min, max);
	}

	private static boolean findPath(int x, int y, int min, int max) throws NoSuchAlgorithmException {
		// mark x,y as a point to be reached
		String key = x + "--" + y;
		if (hashes.contains(key)) {
			return false;
		}
		hashes.add(key);
		if (sumOfSum(x, y) > 21) {
			++rejectCount;
			return false;
		}

		if (x < min || x > max || y < min || y > max) {
			return false;
		}

		++totalPoints;

		// Top
		findPath(x, y - 1, min, max);
		// RIGHT
		findPath(x + 1, y, min, max);
		// Down
		findPath(x, y + 1, min, max);
		// Left
		findPath(x - 1, y, min, max);
		return false;

	}

	private static int sumOfSum(int x, int y) {
		return sumDigits(x) + sumDigits(y);
	}

	public static int sumDigits(int n) {
		n = Math.abs(n);
		int num = 0, sum = 0;
		while (n != 0) {
			num = n % 10;
			sum = sum + num;
			n = n / 10;
		}
		return sum;
	}
}