snippets

public int[][] merge(int[][] intervals) {
    Arrays.sort(intervals, (a, b) -> Integer.compare(a[0], b[0]));
    List<int[]> out = new ArrayList<>();
    for (int[] iv : intervals) {
        if (!out.isEmpty() && iv[0] <= out.get(out.size() - 1)[1]) {
            out.get(out.size() - 1)[1] = Math.max(out.get(out.size() - 1)[1], iv[1]);
        } else {
            out.add(iv);
        }
    }
    return out.toArray(new int[0][]);
}