"""
func extractCities()
    open the file
    read one line to trash header
    create empty list for the cities
    for every additional line in the file
        split the line to get the city
        add the city to the list
    return the list
        """

def extractCities():
    fin = open("IA_population_data.txt","r")
    fin.readline() #throw away the header line
    cities = []
    for line in fin:
        data = line.split("\t")
        city = data[0]
        cities.append(city)
    fin.close()
    
    return cities


"""
function lookFor(list of cities, target city)
    for eachcity in list of cities
        if eachcity is the targetcity
            return True
    return False
"""


def lookFor(cities,target):
    for name in cities:
        if name==target:
            return True
    return False


"""
function lookForBinary(list of cities, target city)
    record the lowest possible place in the list
        the city could be (0)
    record the highest possible place in the list
        the city could be (len(list)-1)
    while there are still cities between those numbers:
        find the middle point
        consider the city at that middle point
        look to see if the current city is your goal
            if it is, return True
        if it is not,
            is the goal AFTER the current city?
                update the lowest possible index to current +1
            else
                update the highest possible index to current-1
    When you reach a point where there are no cities left
        return False

"""




def lookForBinary(cities,target):
    low = 0
    high = len(cities)-1

    while high>=low:
        average = int((low+high)/2)
        print(average, cities[average])
        if (cities[average].upper()==target.upper()):
            return True
        elif (cities[average].upper()<target.upper()):
            low=average+1
        elif (cities[average].upper()>target.upper()):
            high =average-1
    return False