[LeetCode] 846. Hand of Straights

Problem

Alice has a hand of cards, given as an array of integers.

Now she wants to rearrange the cards into groups so that each group is size W, and consists of W consecutive cards.

Return true if and only if she can.

Example 1:

Input: hand = [1,2,3,6,2,3,4,7,8], W = 3
Output: true
Explanation: Alice`s hand can be rearranged as [1,2,3],[2,3,4],[6,7,8].
Example 2:

Input: hand = [1,2,3,4,5], W = 4
Output: false
Explanation: Alice`s hand can`t be rearranged into groups of 4.

Note:

1 <= hand.length <= 10000
0 <= hand[i] <= 10^9
1 <= W <= hand.length

Solution

class Solution {
    public boolean isNStraightHand(int[] hand, int W) {
        int n = hand.length;
        if (n < W || n%W != 0) return false;
        int groups = n/W;
        PriorityQueue<Integer> pq = new PriorityQueue<>();
        for (int card: hand) pq.offer(card);
        
        for (int i = 0; i < groups; i++) {
            int first = pq.poll();
            for (int j = 1; j < W; j++) {
                // if (pq.remove(first+j)) continue;
                if (pq.contains(first+j)) pq.remove(first+j);
                else return false;
            }
        }
        return true;
    }
}