public boolean isNStraightHand(int[] hand, int W) {

if (hand == null) return false;

if (hand.length == 0 && W == 0) return true;

if (hand.length == 0 || W == 0 || hand.length % W != 0) return false;

PriorityQueue<Integer> pq = new PriorityQueue<>();

for (int card: hand) {

pq.add(card);

}

while (!pq.isEmpty()) {

int first = pq.peek();

for (int i = 0; i<W; i++) {

if (!pq.remove(first + i)) {

return false;

}

}

}

return true;

}

/**

public boolean isNStraightHand2(int[] hand, int W) {

TreeMap<Integer, Integer> count = new TreeMap();

for (int card: hand) {

if (!count.containsKey(card))

count.put(card, 1);

else

count.replace(card, count.get(card) + 1);

}

while (count.size() > 0) {

int first = count.firstKey();

for (int card = first; card < first + W; ++card) {

if (!count.containsKey(card)) return false;

int c = count.get(card);

if (c == 1) count.remove(card);

else count.replace(card, c - 1);

}

}

return true;

}

/**

public boolean isNStraightHand3(int[] hands, int W) {

if (W == 1) return true;

if (hands.length % W != 0) return false;

int H = hands.length / W;

int[][] buckets = new int[W][H];

int[] bucketSize = new int[W];

for (int h : hands) {

int indexInBucket = h % W, bucketId = bucketSize[indexInBucket]++;

if (bucketId >= H) return false;

buckets[indexInBucket][bucketId] = h;

}

for (int i = 0; i < W; i++) Arrays.sort(buckets[i]);

for (int i = 0; i < H; i++)

for (int j = 1; j < W; j++)

//consider case 3,1,2 and 3,4,2

if (buckets[j][i] != buckets[j - 1][i] + 1 && buckets[j - 1][i] - buckets[j][i] != W - 1) return false;

return true;

}