Map<Integer, Integer> sleepyMinutes = asleepTime.entrySet().stream()
                .collect(Collectors.<Entry<Integer, List<Range>>, Integer, Integer>toMap(Entry::getKey, e -> {
                    int[] counts = new int[60];
                    for (Range r : e.getValue()) {
                        for (int i = r.getStart(); i < r.getEnd(); i++) {
                            counts[i]++;
                        }
                    }
                    int mxIdx = -1, mx = -1;
                    for (int i = 0; i < sleepCount.length; i++) {
                        if (sleepCount[i] > mx) {
                            mxIdx = i;
                            mx = sleepCount[i];
                        }
                    }
                    return mxIdx;
                }));

        int part2 = sleepyMinutes.entrySet().stream().max(Entry.comparingByValue()).map(e -> e.getKey() * e.getValue()).get();