import random
import bisect


class ObjectsGenerator:
    def __init__(self, pairs):
        self.max_int = 0
        self.diapasons = self.compute_diapasons(pairs)


    def compute_diapasons(self, pairs):
        diapasons = []

        last_end = 0
        for obj, coeff in pairs:
            current_begin = last_end
            last_end = current_begin + coeff - 1
            diapasons.append((current_begin, last_end, obj))
            last_end += 1

        self.max_int = last_end - 1 if pairs else 0
        return diapasons

    def generate_fast(self):
        if len(self.diapasons) == 1:
            return self.diapasons[0]

        bottoms = [x[0] for x in self.diapasons]
        value = random.randint(0, self.max_int)
        print(value)
        return self.diapasons[bisect.bisect_right(bottoms, value) - 1][2]


def test_single_element():
    pairs = [('a', 10)]
    gen = ObjectsGenerator(pairs)
    print(gen.generate_fast())


def test_elements_pair():
    pairs = [('a', 10), ('b', 1)]
    gen = ObjectsGenerator(pairs)
    print(gen.generate_fast())