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  1. from heapq import heappop, heapify, heapreplace, nlargest
  2. from itertools import islice
  3.  
  4.  
  5. def klargest_fullheap(iterable, k):
  6.     heap = [-s for s in iterable]
  7.     heapify(heap)
  8.     return [-heappop(heap) for _ in range(k)]
  9.  
  10.  
  11. def klargest_smallheap(iterable, k):
  12.     heap = list(islice(iterable, k))
  13.     heapify(heap)
  14.     for s in iterable:
  15.         if s > heap[0]:
  16.             heapreplace(heap, s)
  17.     return [heappop(heap) for _ in range(k)]
  18.  
  19.  
  20. def klargest_heapq(iterable, k):
  21.     return nlargest(k, iterable)
  22.  
  23.  
  24. if __name__ == "__main__":
  25.     from random import randrange
  26.     from time import clock
  27.  
  28.     n = 6
  29.     for k_exp in range(n+1):
  30.         k = 10**k_exp
  31.         print("k=", k)
  32.         print("n=", 10**n)
  33.         for method in (klargest_smallheap, klargest_fullheap,
  34.                         klargest_heapq):
  35.             example = (randrange(1, 1000000000) for _ in range(10**n))
  36.             t0 = clock()
  37.             method(example, k)
  38.             print("{:20s} {:6.3f}".format(method.__name__, clock() - t0))
Time limit exceeded #stdin #stdout 5s 12496KB
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https://ideone.com/kqHpJX
language:
Python 3 (python  3.9.5)
created:
7 years ago
visibility:
secret

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