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  1. import std.stdio : writeln;
  2. import std.algorithm.comparison: min;
  3. import std.algorithm.iteration: sum;
  4. import core.time: MonoTime, Duration;
  5.  
  6.  
  7. auto sum_subranges(T)(T input, uint range)
  8. {
  9.     import std.range : chunks, ElementType, array;
  10.     import std.algorithm : map;
  11.  
  12.     if (range == 0)
  13.     {
  14.         return ElementType!(T)[].init;
  15.     }
  16.     return input.chunks(range).map!(sum).array;
  17. }
  18.  
  19. unittest
  20. {
  21.     assert(sum_subranges([1,1,1], 2) == [2, 1]);
  22.     assert(sum_subranges([1,1,1,2,3,3], 2) == [2, 3, 6]);
  23.     assert(sum_subranges([], 2) == []);
  24.     assert(sum_subranges([1], 2) == [1]);
  25.     assert(sum_subranges([1], 0) == []);
  26. }
  27.  
  28.  
  29. void main()
  30. {
  31.     import std.range : iota, array;
  32.     auto v = iota(0,1000000).array;
  33.     int sum;
  34.     MonoTime beg = MonoTime.currTime;
  35.     for (int i=0; i < 100; i++)
  36.         sum += cast(int)sum_subranges(v,2).length;
  37.     MonoTime end = MonoTime.currTime;
  38.     writeln(end-beg);
  39.     writeln(sum);
  40. }
Success #stdin #stdout 3.27s 15800KB
comments (?)
stdin
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Standard input is empty
stdout
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3 secs, 260 ms, 631 μs, and 3 hnsecs
50000000
https://ideone.com/TRDsOo
language:
D (gdc 8.3)
created:
7 years ago
visibility:
public

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