public static int hackerlandRadioTransmitters(List<Integer> x, int k) {
        int counter = 0;
        int trans = 0;
        int minInRange = 0;
        
        x = x.stream().distinct().sorted().collect(toList());
        for(int n:x){
            if(trans == 0){
                trans = n;
                counter++;
            } else if(inRange(trans, n, k)){
                if (minInRange == 0){
                    minInRange = trans;
                    trans = n;
                } else if (inRange(minInRange, n, k)){
                        trans = n;
                }
            } else {
                trans = n;
                minInRange = 0;
                counter++;
            }
        }
        
        return counter;
    }

public static int hackerlandRadioTransmitters(List<int> houses, int range)
{
    houses.Sort();
    
    int transmittersCount = 0;
    int i = 0;
    
    while (i < houses.Count)
    {
        transmittersCount++;
        
        // Take the first house. 
        int left = houses[i];
        int mid = left + range;
        
        // Find the first house out of range, put a transmitter 1 house before there.
        while (i < houses.Count && houses[i] <= mid)
        {
            i++;
        }
        
        mid = houses[i-1];
        int right = mid + range;
        
        // Find the first house out of range. Repeat.
        while (i < houses.Count && houses[i] <= right)
        {
            i++;
        }
    }
    
    return transmittersCount;
}

public static int hackerlandRadioTransmitters(List<Integer> x, int k) {
    // Write your code here
        if(x.size() < 1)
            return 0;
            
        int maxInd = x.stream().max(Comparator.comparingInt(Integer::intValue)).get();
        int minInd = x.stream().min(Comparator.comparingInt(Integer::intValue)).get();
        
        Set<Integer> houseIndex = new HashSet<>(x);
        int count = 0;
        int currentInd = minInd;
        while(currentInd <= maxInd) {
            if(houseIndex.contains(currentInd)) {
                count++;
                for(int i = k; i >= 0; i--) { // look for farthest house in range for radio installation 
                    if(houseIndex.contains(currentInd + i)) {
                        currentInd += i; //here radio installed
                        break;
                    }
                }
                currentInd += k;// till this range coverage is available
            }
            currentInd++; // move to find next house for coverage
        }
        return count;
    }

def hackerlandRadioTransmitters(x, k):
    size = len(x)
    if size == 1:
        return 1
        
    x.sort()
    num = 0
    i = 0
    while i < size:
        # mark the furthest location within the coverage at current i
        loc = x[i] + k
   
        # move to the furthest house within the range and set transmitter
        while i < size and x[i] <= loc:
            i += 1
        i -= 1
        num += 1
        
        # make the furthest location within the coverage at current i
        loc = x[i] + k
        
        # move to the first house outside the coverage
        while i < size and x[i] <= loc:
            i += 1
        
    return num