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  1. def inv_count(a, m=(1<<32)):
  2.   if not m or not a:
  3.       return 0
  4.   count = 0
  5.   ones = []
  6.   zeros = []
  7.   for n in a:
  8.     if n & m:
  9.       ones.append(n & ~m)
  10.     else:
  11.       count += len(ones)
  12.       zeros.append(n & ~m)
  13.   m /= 2
  14.   return count + inv_count(ones, m) + inv_count(zeros, m)
  15.  
  16.  
  17. print inv_count([1, 2, 3, 4, 5])
  18. print inv_count([5, 4, 3, 2, 1])
Success #stdin #stdout 0.01s 7692KB
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https://ideone.com/g57O87
language:
Python (cpython 2.7.16)
created:
8 years ago
visibility:
public

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