74. Hand of Straights

Topic :

priority queue

Difficulty :

medium

Problem Link :

problem statement

Alice has some number of cards and she wants to rearrange the cards into groups so that each group is of size groupSize, and consists of groupSize consecutive cards.

Given an integer array hand where hand[i] is the value written on the ith card and an integer groupSize, return true if she can rearrange the cards, or false otherwise.

Example 1:

Input: hand = [1,2,3,6,2,3,4,7,8], groupSize = 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], groupSize = 4
Output: false
Explanation: Alice's hand can not be rearranged into groups of 4.

Constraints:

1 <= hand.length <= 104
0 <= hand[i] <= 109
1 <= groupSize <= hand.length

solution

import java.io.*;
import java.util.*;
 class HandOfStraights
{
  public static void main(String args[])
  {
      int []hand={1,2,3,6,2,3,4,7,8}; int groupSize=3;
      System.out.println(isStraightHand(hand,groupSize));
  }
  static boolean isStraightHand(int[] hand, int groupSize) {
        PriorityQueue<Integer> pq=new PriorityQueue<>(); //minHeap
        for(int card : hand)
            pq.offer(card);
        
        while(!pq.isEmpty())
        {
            int startCard=pq.poll();
            for(int i=1;i<groupSize;i++)
            {
                if(pq.remove(startCard+i))
                 continue;
                else 
                 return false; // the next consequtive card is not present
            }
        }
        return true;
    }
}