Cinema Seat Allocation

class Solution {
    public int maxNumberOfFamilies(int n, int[][] reservedSeats) {
        int count = 0;
        
        Arrays.sort(reservedSeats, new Comparator<int[]>() {
				public int compare(int[] a, int[] b) {
					if(a[0] != b[0])return a[0] - b[0];
					return a[1] - b[1];
				}
			});
        int ret = 2*n;
        for(int i = 0; i<reservedSeats.length; ){
            int j = i;
            while(j < reservedSeats.length && reservedSeats[j][0] == reservedSeats[i][0]){
                j++;
            }
            
            ret -= 2;
	        int ptn = 0;
	        for(int k = i;k < j;k++){
	        	ptn |= 1<<reservedSeats[k][1];
	        }
	        if((ptn&((1<<10)-(1<<2))) == 0){
	        	ret += 2;
	        }else if((ptn&((1<<8)-(1<<4))) == 0){
	        	ret++;
	        }else if((ptn&((1<<6)-(1<<2))) == 0){
	        	ret++;
	        }else if((ptn&((1<<10)-(1<<6))) == 0){
	        	ret++;
	        }
	        	
	        i = j;
        }
        return ret;
    }
}