Day17.java

public class Day17 {

	private static final int TARGET = 150;

	private int[] buckets = { 11, 30, 47, 31, 32, 36, 3, 1, 5, 3, 32, 36, 15,
			11, 46, 26, 28, 1, 19, 3 };
	private int minBuckets;

	public static void main(String[] args) {
		Day17 day17 = new Day17();

		System.out.println("Part 1: " + day17.solvePart1());
		System.out.println("Part 2: " + day17.solvePart2());

	}

	public int solvePart1() {
		int count = 0;
		minBuckets = Integer.MAX_VALUE;
		for (int bitmap = 1; bitmap < 1 << buckets.length; bitmap++) {
			if (checkValid(bitmap)) {
				count++;
				int bitCount = countBits(bitmap);
				if (minBuckets > bitCount) {
					minBuckets = bitCount;
				}
			}
		}
		return count;
	}

	public int solvePart2() {
		int count = 0;
		for (int bitmap = 1; bitmap < 1 << buckets.length; bitmap++) {
			if (checkValid(bitmap) && (countBits(bitmap) == minBuckets)) {
				count++;
			}
		}
		return count;
	}

	private boolean checkValid(int bitmap) {
		int sum = 0;
		for (int i = 0; i < buckets.length; i++) {
			if ((bitmap & (1 << i)) == (1 << i)) {
				sum += buckets[i];
				if (sum > Day17.TARGET) {
					return false;
				}
			}
		}
		if (sum == Day17.TARGET) {
			return true;
		}
		return false;
	}

	private int countBits(int bitmap) {
		int count = 0;
		for (int i = 0; i < buckets.length; i++) {
			if ((bitmap & (1 << i)) == (1 << i)) {
				count++;
			}
		}
		return count;
	}
}