adventures.py

class Solution(object):

    def __init__(self):
        self.arr = []

    def add_product(self, name, locations):
        self.arr.append((name, locations))

    def get_locations(self):
        data = {}
        for item in self.arr:
            for location in item[1]:
                if location not in data:
                    data[location] = set()
                data[location].add(item[0])
        return [(x[0], list(x[1])) for x in data.items()]


s = Solution()
s.add_product('ABC', ["Paris", "France", "Europe"])
s.add_product('DEF', ["Dubai", "Abu Dhabi", "UAE"])
s.add_product('XYZ', ["Germany", "Italy", "Paris", "Europe"])
print s.get_locations()