merge sort                          selection sort
    N        operations           time             operations           time               ratio
 -------     ----------   --------------------     ----------   --------------------      --------
 1.0e+03      4.983e+04    49.83 micro-seconds      5.000e+05   500.00 micro-seconds      1.00e+01
 1.0e+04      6.644e+05   664.39 micro-seconds      5.000e+07     50.00 milliseconds      7.53e+01
 1.0e+05      8.305e+06      8.30 milliseconds      5.000e+09              5 seconds      6.02e+02
 1.0e+06      9.966e+07     99.66 milliseconds      5.000e+11            8.3 minutes      5.02e+03
 1.0e+07      1.163e+09            1.2 seconds      5.000e+13               14 hours      4.30e+04
 1.0e+08      1.329e+10             13 seconds      5.000e+15             1.9 months      3.76e+05
 1.0e+09      1.495e+11            2.5 minutes      5.000e+17               16 years      3.34e+06
 1.0e+10      1.661e+12             28 minutes      5.000e+19            1,584 years      3.01e+07
 1.0e+11      1.827e+13              5.1 hours      5.000e+21          158,440 years      2.74e+08
 1.0e+12      1.993e+14               2.3 days      5.000e+23       15,844,043 years      2.51e+09