----------------  SOLUTION  -------------------

solution cost   : 358.402
number of trips : 4

trip 1, 6 customers, sequence : 14 13 16 18 10 12 
   weight    : 83
   volume    : 6
   trip cost : 118.567

trip 2, 3 customers, sequence : 2 8 17 
   weight    : 85
   volume    : 3
   trip cost : 49.9474

trip 3, 6 customers, sequence : 5 20 11 19 6 1 
   weight    : 77
   volume    : 6
   trip cost : 103.332

trip 4, 5 customers, sequence : 4 15 3 9 7 
   weight    : 84
   volume    : 5
   trip cost : 86.5564