public static boolean canAttendMeetings_bf(int[][] intervals) {
    int len = intervals.length;
    if (len <= 1) {
        return true;
    }

    for (int i = 0; i < len; i++) {
        for (int j = i + 1; j < len; j++) {
            int[] m1 = intervals[i];
            int[] m2 = intervals[j];

            if (!(m1[1] <= m2[0] || m1[0] >= m2[1])) {
                return false;
            }
        }
    }

    return true;
}

public static boolean canAttendMeetings(int[][] intervals) {
    if (intervals == null || intervals.length <= 1) {
        return true;
    }

    Arrays.sort(intervals, (a, b) -> {
        if (a[0] == b[0]) {
            return a[1] - b[1];
        }
        return a[0] - b[0];
    });

    for (int i = 1; i < intervals.length; i++) {
        if (intervals[i][0] < intervals[i - 1][1]) {
            return false;
        }
    }

    return true;
}

public int minMeetingRooms(int[][] intervals) {
    if (intervals == null || intervals.length <= 1) {
        return intervals.length;
    }

    int len = intervals.length;

    Arrays.sort(intervals, (a, b) -> a[0] == b[0] ? a[1] - b[1] : a[0] - b[0]);

    PriorityQueue<int[]> pq = new PriorityQueue<>(new Comparator<int[]>() {
        @Override
        public int compare(int[] a, int[] b) {
            return a[1] == b[1] ? a[0] - b[0] : a[1] - b[1];
        }
    });

    int min = 1;

    pq.offer(intervals[0]);

    for (int i = 1; i < len; i++) {
        int start = intervals[i][0];
        int end = intervals[i][1];
        
        if (!pq.isEmpty() && start < pq.peek()[1]) {
            pq.offer(intervals[i]);
            min = Math.max(min, pq.size());
        } else {
            pq.poll();
            pq.offer(intervals[i]);
        }
    }

    return min;
}