len  	Total time	time/(n*log2(n)
      64,	0.00001579 	0.000000041116
     128,	0.00002620 	0.000000029244
     256,	0.00005526 	0.000000026980
     512,	0.00011780 	0.000000025564
    1024,	0.00025464 	0.000000024867
    2048,	0.00055217 	0.000000024510
    4096,	0.00118479 	0.000000024105
    8192,	0.00253496 	0.000000023803
   16384,	0.00526464 	0.000000022952
   32768,	0.01173529 	0.000000023876
   65536,	0.03234014 	0.000000030842
  131072,	0.12145482 	0.000000054507
  262144,	0.30355562 	0.000000064332
  524288,	0.78241536 	0.000000078544
 1048576,	1.66776867 	0.000000079525
 2097152,	3.54513800 	0.000000080498