Method compare

NumberOfSmallestUnoccupiedChair.java:6–8

(int a[], int b[])

        int targetArrival = times[targetFriend][0]; //[a,d]
        Arrays.sort(times, new Comparator<int[]>(){
            public int compare(int a[], int b[]){
                return a[0] - b[0];
            }
        });
        //[lt,chairNo]
        PriorityQueue<int[]> occupied = new PriorityQueue<>(new Comparator<int[]>(){