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  1. Journey to the Moon
  2. Discussions

Journey to the Moon

  • virgul
     + 0 comments

    Python solution using combinations. I calculate all the combinations and substract the pairs from the same country. Firstly I divide astronauts into countries and later I calculate number of combinations for each country.

    from math import factorial

def combinations(n,k):
    return factorial(n)/(factorial(k)*factorial(n-k))

def journeyToMoon(n, astronaut):
    countries = []
    for p in astronaut:
        x,y = p
        if len(countries) == 0:
            countries.append(astronaut[0])
        i = 0
        a = None
        b = None
        while i < len(countries):
            if x in countries[i]:
                a = i
            if y in countries[i]:
                b = i
            i+=1
        if a == None and b == None:
            countries.append(p)
        elif a == None and b != None:
            countries[b].append(x)
        elif a != None and b == None:
            countries[a].append(y)
        elif a!=b:
            countries[a].extend(countries[b])
            countries.remove(countries[b])
    pairs = 0
    for c in countries:
        if len(c) > 1:
            pairs += combinations(len(c),2)
    return int(combinations(n,2)-pairs)