union(S,T): returns the union of sets S and T

intersection(S,T): returns the intersection of sets S and T

difference(S,T): returns the difference of sets S and T

subset(S,T): a predicate that tests whether the set S is a subset of set T

#!/usr/bin/python

class Set(object):
    def __init__(self):
        self._d = {}

    @property
    def d(self):
        return self._d

    @d.setter
    def d(self, d):
        self._d = d

    @d.deleter
    def d(self):
        del self._d

    def insert(self, v):
        """Insert an object into set"""
        self.d[v] = 0

    def union(self, s):
        temp = Set()
        for e in s.d:
            temp.insert(e)

        for e in self.d:
            temp.insert(e)

        return temp

    def intersection(self, s):
        temp = Set()
        for i in self.d:
            if s.d.has_key(i):
                temp.insert(i)

        return temp

    def difference(self, s):
        temp = Set()
        for i in self.d:
            if not s.d.has_key(i):
                temp.insert(i)

        return temp

    def subset(self, s):
        for i in self.d:
            if not s.d.has_key(i):
                return False

        return True

    def __str__(self):
        s = ''
        for e in self.d:
            s += str(e)+' '

        return s

def main():
    s = Set()
    s.insert(1)
    s.insert(2)
    s.insert(3)
    s.insert(4)

    s2 = Set()
    s2.insert(1)
    s2.insert(10)
    s2.insert(2)
    s2.insert(20)

    # union
    u = s.union(s2)
    print(u)

    # intersection
    i = s.intersection(s2)
    print(i)

    # difference
    d = s.difference(s2)
    print(d)

    # subset
    print(s.subset(s2))

if __name__ == '__main__':
    main()
			

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