public static int hackerlandRadioTransmitters(List<Integer> x, int k) {
        Collections.sort(x);

        int transmitters = 0;
        int i = 0;

        while (i < x.size()) {
            int location = x.get(i);
            transmitters++;
            int nextCoverage = location + k;

            while (i < x.size() && x.get(i) <= nextCoverage) {
                i++;
            }

            int lastHouseInRange = x.get(i - 1);

            while (i < x.size() && x.get(i) <= lastHouseInRange + k) {
                i++;
            }
        }

        return transmitters;
    }