     n   brute (ms)   sorted (ms)   same answer?
  2000         0.63         0.125   yes
  4000         2.46         0.230   yes
  8000         9.87         0.480   yes
 16000        41.79         0.994   yes
 32000       173.16         2.452   yes
 64000       670.66         4.631   yes
small example {8,3,6,3,9,1}: x=12 -> 1 1, x=16 -> 0 0
