find 1 mil smallest number in 1 bil input number

1smallestin1bil.py

# origin question&answer 
# http://www.vithon.org/2015/04/30/ph%E1%BB%8Fng-v%E1%BA%A5n:-tim-1-tri%E1%BB%87u-s%E1%BB%91-nh%E1%BB%8F-nh%E1%BA%A5t-trong-1-t%E1%BB%B7-s%E1%BB%91
# the origin version use heapq
# this version do not use external module, but use sorted cheat when iterate through set (is not sorted)

def solve(inp, n=1000000):
    print inp
    heap = set()
    for i in inp:
        i = -i
        if len(heap) < n:
            heap.add(i)
        else:

            for m in sorted(heap):
                if m < i and i not in heap:
                    heap.remove(m)
                    heap.add(i)
    return [-x for x in heap]

assert(set(solve([1, 2, 3, 4, -5], 3)) == set([-5, 1, 2]))
assert(set(solve([5, 4, 3, 2, 1], 3)) == set([1, 2, 3]))
assert(set(solve([13, 4, 3, 2, 1, 100, 2000, 500], 5)) == set([1, 2, 3, 4, 13]))