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  1. import timeit
  2.  
  3. def basic_bitwise_xor(integers):
  4.     result = 0
  5.     for n in integers:
  6.         result ^= n
  7.     return result
  8.  
  9. def unrolled_bitwise_xor(integers):
  10.     result = 0
  11.     count = len(integers)
  12.     unrolled_count = count & ~7
  13.     leftover = count & 7
  14.     i = 0
  15.  
  16.     while i < unrolled_count:
  17.         result ^= integers[i    ]
  18.         result ^= integers[i + 1]
  19.         result ^= integers[i + 2]
  20.         result ^= integers[i + 3]
  21.         result ^= integers[i + 4]
  22.         result ^= integers[i + 5]
  23.         result ^= integers[i + 6]
  24.         result ^= integers[i + 7]
  25.         i += 8
  26.  
  27.     if leftover & 4:
  28.         result ^= integers[i    ]
  29.         result ^= integers[i + 1]
  30.         result ^= integers[i + 2]
  31.         result ^= integers[i + 3]
  32.         i += 4
  33.  
  34.     if leftover & 2:
  35.         result ^= integers[i    ]
  36.         result ^= integers[i + 1]
  37.         i += 2
  38.  
  39.     if leftover & 1:
  40.         result ^= integers[i]
  41.  
  42.     return result
  43.  
  44. print('basic time:', timeit.timeit('basic_bitwise_xor(l)',
  45.                                    'l=list(range(100))',
  46.                                    globals=globals(),
  47.                                    number=100000))
  48. print('unrolled time:', timeit.timeit('unrolled_bitwise_xor(l)',
  49.                                       'l=list(range(100))',
  50.                                       globals=globals(),
  51.                                       number=100000))
Success #stdin #stdout 0.63s 14148KB
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basic time: 0.2191149890422821
unrolled time: 0.3471912555396557
https://ideone.com/5a9ZdK
language:
Python 3 (python  3.12)
created:
238 days ago
visibility:
secret

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