Cinema Seat Allocation LeetCode solution in Java

1
class Solution {
2
  public int maxNumberOfFamilies(int n, int[][] reservedSeats) {
3
    Map<Integer, int[]> seats = new HashMap<>();
4
    int availableSlots = 2 * n; // max available slots since each empty row could fit at max 2 slots
5

6
    for (int[] seat : reservedSeats) {
7
      int row = seat[0];
8
      int col = seat[1];
9
      int[] slots = seats.getOrDefault(row, new int[3]);
10

11
      if (col >= 2 && col <= 5) { // left slot
12
        slots[0] = 1;
13
      }
14
      if (col >= 4 && col <= 7) { // middle slot
15
        slots[1] = 1;
16
      }
17
      if (col >= 6 && col <= 9) { // right slot
18
        slots[2] = 1;
19
      }
20

21
      seats.put(seat[0], slots);
22
    }
23

24
    for (int[] slots : seats.values()) {
25
      int taken = slots[0] + slots[2];
26

27
      if (taken == 2) { // both slots at either ends are taken
28
        if (slots[1] == 0) { // check if middle slot not taken
29
          availableSlots--; // reduce availableslots by 1 since middle slot is available
30
        } else {
31
          availableSlots -= 2; // entire row not available - reduce by 2
32
        }
33
      } else if (taken == 1) { // one of the slots at either ends are taken
34
        availableSlots--; // reduce by 1 since either side of the slots not available
35
      } else {
36
        continue; // entire row is available - no need to reduce the available slots
37
      }
38
    }
39

40
    return availableSlots;
41
  }
42
}