# two modes: 
# a) looking for farthest house to provide covarege for current uncovered house (radio search)
# b) looking for first house out of coverage from current house with radio

def hackerlandRadioTransmitters(locs, coverage):
    locs.sort()
    if len(locs) == 1:
        return 1

    radiosearch = True
    curindex = 0
    numradios = 0
    
    while True:
        otherindex = curindex + 1
        while otherindex != len(locs) and locs[otherindex] - locs[curindex] <= coverage:
            otherindex += 1
            
        if radiosearch:
            numradios += 1
            curindex = otherindex - 1 # radio search ends one house too far
        else:
            curindex = otherindex
            
        if otherindex == len(locs):
            return numradios
        
        radiosearch = not radiosearch